Blue Masters... Mainly from convenience, but also from experience. The Blue Masters is most commonly found and used. In my experience, the Green and other colors Masters, along with Silver Cup chalk don't hold quite as well. The others leave more bare spots on the tip. Whereas the Blue Masters is more effective at covering the tip.
As long as you use the same chalk consistently, then it makes little difference. If you use a better chalk normally, and wind up using a lesser chalk, then you will notice the increase in miscues, and may recognize that you have to reduce the amount of spin on the ball.
If I was going to switch, I'd use Blue Triangle. Tried it out in Vegas and was quite impressed with it. It covered the tip well, held better, and was definitely less messy than the others.
Currently, I don't need chalk that holds longer than Masters Blue, because part of my pre-shot routine is to lightly chalk up the cue, while viewing my next shot. Using the Triangle with my pre-shot routine, I'd probably chalk up 10 times more than I need to, or else would have to mentally think about when I should chalk, which would be distracting.
P.S. Welcome to the Board.