The last time I thought a control deck was good was a brief period where Dragonlord Ojutai and Silumgar's Scorn were available. I don't have an irrational hate of control (although I'm certainly more midrange-leaning these days), but there haven't been many points in the recent years where control was actually the best deck.
Everything is different now.
Not only do we have Teferi, Hero of Dominaria as one of the best cards in Standard, but we also have Deafening Clarion, which is necessary to fight Selesnya Tokens. Having something that cleans up the random value dorks is nice because otherwise you couldn't keep up with decks like Golgari. Ritual of Soot is another option (which would push you toward Esper), but that leads to your deck having too many four-drops, which is unacceptable.
Additionally, there are very few ways to punish a control deck for tapping out. A Dimir-based control deck has Vraska's Contempt to clean up some of those scary permanents, but the necessity for such a thing is marginal. Karn, Scion of Urza might be the scariest card, but very few people are playing it, plus it's not that difficult to go over the top of it anyway.
Then there's Expansion, which is the big sell for Jeskai. Not only do you have a sizeable advantage in control mirrors thanks to the ability to win nearly every counterwar but having an X spell capable of ending the game is excellent. In a pinch, it can function as another removal spell when combined with one of your own.
Building the rest of the deck is dependent on the context of the metagame.
Mixing tapout control with a bunch of counterspells typically isn't a great recipe. Teferi fixes that somewhat by allowing you to "tap out" for a threat and still have mana available to defend him. There are certainly issues with tapping out for Deafening Clarion or Ixalan's Binding and getting wrecked by your opponent following up with a planeswalker or something similar, but as I noted earlier, that's not exactly an issue at the moment. Thankfully, there aren't many threats that you can't answer outright.
Teferi, Search for Azcanta, and Chemister's Insight provide the backbone for the deck. You need some amount of card advantage to keep up with your opponents', plus having the extra filtering protects you from mana issues and makes your gameplan more consistent. One of my main worries for control is the mana curve and potential clunkiness in general, but we have various comeback mechanisms should things develop poorly in the early game.
The manabase is also important, especially when you're a three-color deck in a sea of leaner two-color decks. You can't afford to fall behind because of your manabase, so I take great care in ensuring I have the right mix of shocklands and basics to enable my checklands. A ratio of eleven checklands to fifteen enablers is a reasonable place to be, so there's no need for Evolving Wilds. I even managed to fit in one copy of Field of Ruin because Search for Azcanta is one of the very few permanents you'll need to be able to answer.
With fifteen sources of blue, sixteen sources of red, and fourteen sources of white (not counting Field of Ruin, even though it can fix your mana in a pinch), we should be able to cast our spells in a timely manner. We need to hit our land drops early and often, especially with Explosion as a lategame payoff, so 27 land seems right. Some lists from Magic Online even play 28!
An extra blue source would be helpful because we want countermagic early. Fourteen sources of white might be excessive, especially since I'm trying to keep the white splash to a minimum, so I could see making that sort of swap. If opposing Search for Azcantas don't scare you, the Field of Ruin could become an Island.
When talking about control decks, I've mentioned how splashing a third color is a better choice than trying to play all three colors in equal amounts. What you sacrifice in power, you more than make up for in consistency. On top of that, you're playing three colors and a plethora of gold cards, so your deck is probably more powerful than your opponents' on average. Given that, you can probably afford to sacrifice some power for consistency.
One of the biggest arguments for playing Jeskai over Esper is because of the manabase. You have two shocklands instead of one, which makes your checklands much better. To top it off, there is very little CC in the various mana costs, whereas Esper needs UU and BB relatively early. Casting Ionize and Deafening Clarion is much easier than trying to cast Sinister Sabotage and Vraska's Contempt.
I'm effectively splashing Teferi, Ixalan's Binding, Deafening Clarion, Justice Strike, and Settle the Wreckage. In total, this deck has fourteen white spells maindeck, which is low, especially compared to twenty blue spells and fifteen red spells. Aside from Deafening Clarion, you usually don't need white mana very early on anyway. It's possible we can go even lower on white cards, as Justice Strike isn't entirely necessary.
For the most part, Lightning Strike covers your bases against many things, including some planeswalkers, but it's a little awkward to overlap with Deafening Clarion, leaving you with a bunch of removal that can't remove a four-toughness creature. That's mostly why Justice Strike, Ixalan's Binding, and Settle the Wreckage need spots.
Splashing Settle the Wreckage isn't ideal, but the necessity for a sweeper dictates that you play either Settle the Wreckage or Cleansing Nova. There are certainly upsides to playing Cleansing Nova, and I've gotten completely destroyed by it when playing decks with a bunch of weird permanents, so maybe having one as a sideboard option would be useful.
There's always a spread of countermagic in people's control decks, and very rarely is the exact composition the same. I tend to value mana efficiency, especially in the early game, while others tend to lean toward power. Essence Scatter is as incredible as always, but there are both fewer threats that you must answer immediately and fewer scary creature threats in general. The value creatures are small and can be swept up with Deafening Clarion, whereas the big threats are typically vulnerable to spot removal.
History of Benalia is a truly terrifying card, hence the copies of Syncopate. Negate isn't great against everyone, so you need Syncopate as a hedge. Given the lack of spells you absolutely need to counter, I don't think you need four copies of a Cancel variant. Again, reducing the clunkiness of the deck is of the utmost importance. That's why I'm only playing three copies of Chemister's Insight, but that could be a mistake given how good this deck is at trading one-for-one.
The sideboard needs to give you alternative plans against Golgari, Mono-Red Aggro, and control mirrors. For the most part, the maindeck is configured to fight decks like Selesnya Tokens and they aren't able to alter their main gameplan after sideboard, so your maindeck plan will still work.
For Mono-Red, we have copies of Seal Away to deal with large Runaway Steam-Kins and Rekindling Phoenix, although Lava Coil is another option. Since some folks are still playing Nullhide Ferox, having the hard removal spell looks more appealing at the moment. Seal Away also works better with Teferi.
The Shalai, Voice of Plenty / Lyra Dawnbringer package can come in a variety of places, but they're mostly there to fight Mono-Red Aggro. Some people play more copies of Lyra, but having a mix of Shalai and Lyra seems better to me. You'd rather draw a mix of both, especially when they're almost equally effective against the deck and don't cost the same amount of mana.
If your control or midrange opponents aren't expecting the Angel plan and take out their removal, you could potentially ambush them. Golgari will probably have answers regardless, since their answers to Teferi will also tag your Angels. However, a Jeskai opponent may have no such luxury aside from Teferi.
Nezahal, the Primal Tide is good again. Disallow made it mostly irrelevant, but now there aren't any good answers. Esper Control plays a maindeck Chromium, the Mutable, and it's significantly worse than Nezehal. Dealing with it permanently isn't nearly as difficult as trying to fight through Nezahal.
The extra card advantage in the sideboard looks weird to me, but I think it's right. Against midrange and control, you definitely want extra copies of Chemister's Insight and Search for Azcanta, but if you're playing them in the sideboard, you can often find a more specific, narrow card for those matchups. In this case, I don't think that's actually true.
Cards I'm Not Playing, But Could Be
As a filtering tool, Azor's Gateway isn't great. Being disincentivized from exiling multiple lands with it makes it much worse. However, once you transform it, the life total boost and incredible synergy with Expansion are both excellent.
The other cards are various threats and answers you could play but seem worse than the options I've included. Still, it's important to see what other people are doing to ensure you aren't missing anything. The Sarkhan, Fireblood / Niv-Mizzet, Parun package is likely worth pursuing at some point.
Sideboarding and Matchup Guide
As always, this sideboarding guide should merely be a starting point, not gospel. Since Standard is relatively fresh, people's decklists are going to vary from person to person, as will their plans against you. Some decks, like Golgari, rarely look the same, so you shouldn't be sideboarding the same way against every person with Overgrown Tomb in their deck.
VS Mono-Red Aggro
For the most part, I like the plan of having more removal for Rekindling Phoenix, win conditions that function as defensive tools, and shaving a lot of the clunky cards. If your opponent has a slower red deck with multiple Experimental Frenzies, Treasure Maps, and/or Siege-Gang Commanders, having more powerful cards like Search for Azcanta and Teferi is a necessity. Experimental Frenzy is the main reason Ixalan's Binding is even in my deck. A better plan for beating Experimental Frenzy might be establishing a clock, but Ixalan's Binding still works quite well.
The scariest versions of red are the ones with Viashino Pyromancer and Wizard's Lightning because most of your cards don't interact well against direct damage. Sideboarding in Shalai and Lyra helps a lot but might not be enough. If they're packing a lot of burn and/or Experimental Frenzy, Negate's stock goes way up.
VS Selesnya Tokens
Sideboarding here should be relatively easy because most people will be copying the winner from #SCGCOL . Spot removal is weak, counterspells are decent, and although Search for Azcanta is powerful in part because it's so cheap, you won't necessarily have time to cast Chemister's Insight.
Anything that deals with creatures isn't great here, although you might have to deal with History of Benalia from other Azorius decks. Maybe some Deafening Clarions should stay in against those matchups as a result. I wouldn't be surprised if the Angel plan wasn't very good here, but it seemed easy to put down on the list because of how many dead cards there are.
VS Golgari Midrange
Golgari is one of the matchups where you will end up varying your sideboarding the most. No two lists are exactly the same.
In general, you'll want some additional card advantage and counterspells for their powerful spells like The Eldest Reborn and Vraska, Relic Seeker. Spot removal tends to be poor since their deck will mostly consist of value creatures. If they're trying to Vraska you, counterspells will be your best friend. If they're slightly aggressive with Doom Whisperer, Molderhulk, or Izoni, Thousand-Eyed, you'll want more removal (and maybe the Angels).
The Perfect Answer
Since the metagame is set, I'm more than happy to endorse this version of Jeskai Control as the perfect answer. You have powerful cards, a reasonable manabase, and excellent sideboard options. Plus, Teferi and Deafening Clarion will beat many decks on their own. It's a good enough time to be a control mage that even I'm hopping on board.