Choosing the right deck for an upcoming tournament is one of the most challenging situations to approach in all of Magic. If you show a collection of the world's best players a keep-or-mulligan decision or a what's-the-play scenario, a lot of the answers you receive will tend towards similar results. Yet when you make that same group of the world's best players choose a deck to play at a tournament, you'll end up with a vast array of different decks, all with different justifications behind these choices.
What information should you try to process and understand when deciding on a deck for a tournament, and how can you use this information to help make the best deck choice for you?
Deck selection is not only a skill we just generally underrate, but also one we rarely actively encourage or teach people to improve. We look at choosing a deck for a tournament as something you stress over in the week leading up the event. Finally you lock in your decklist, and once the tournament is over, you immediately move on and dive headlong into preparing for next week's event. Instead I want to look at deck selection as a process that you can iterate on from one tournament to the next, refining your approach each time you go to a tournament via self-awareness and reflection.
This is my philosophy of how to approach deck selection, which I have attempted to follow and constantly improve over the last couple of years. I hope that this article can help you gain a clearer sense of how to improve your approach to deck selection also.
Everything you do when you're selecting a deck for a tournament should be done with the aim of maximizing your win percentage in that tournament. In a very broad sense, every question you're asking yourself should be through the lens of "Does this maximize my win percentage?". Often the answer to this question is "I don't know," as it being hard to answer is essentially the reason this article exists, but keeping this question in mind is key to maintaining the correct perspective.
Looking through this lens, it's easy to see how deck selection becomes immediately personal. The win percentages you can achieve with the various decks in a format depend strongly on your personal skills and abilities. When your aim is not to choose some definitive best deck for the tournament, but rather to choose the deck that you will win with the most and that will therefore be the best deck for you, it becomes difficult for anyone else to make this choice for you. You understand your strengths and weaknesses more than anyone else, you have to take responsibility for your choices, and you'll be the one shuffling up for your first round at 9am on Saturday morning. It doesn't matter if Brad Nelson would win the most with Sultai Midrange if the deck you'll win the most with is Esper Control.