Watching coverage of GP Birmingham, I was really impressed by Leo Lahonen's U/W Control deck:
I love the move away from creatures, as blanking the opponent's removal is great in this format. I'd been playing decks that focused on doing this, but I went further, and tried to blank Vraska's Contempt by not playing planeswalkers either. After trying a few configurations, I settled on The Mirari Conjecture loops with Blink of an Eye that eventually killed by copying and/or rebuying Fight with Fire.
I like the value The Mirari Conjecture generated, and I liked that the Fight with Fire kill just required playing one or two copies of a mediocre removal spell to give my deck a win condition. What I didn't like was how much harder I had to work to get my card advantage than I would if I were just playing Teferi. When your deck is all reactive spells and you're looping The Mirari Conjecture, chapter three doesn't actually do anything for you most of the time, and when you're returning Blink of an Eye with chapter one, you're basically just spending nine mana to draw a card and add Commit to your hand every few turns. That's not bad, but if your opponent isn't doing anything, it doesn't really get you anywhere; you just end up with a full hand and discarding a lot.