Interesting question. I can make a case for any one of the three, and even for any one of the remaining two for game #2.
IMO it's going to be David Price. He's the guy making the most money, put up 17 wins last year in spite of the rocky start, and frankly IMO he'd be the one who'd be the most offended if he didn't get to start game #1. Ya gotta take care of those egos!
Porcello seems to be a guy who sees himself as a supporting player, someone who doesn't have the need to be in the spotlight, but IMO he'd get game #2 because, after all, he IS the CY winner! - and has the most seniority of the three Aces. (and we do have three aces now).
Sale gets Game #3 by default, but I see him as being enough of a competitor that he'll be challenging the other two all season long.
I can see all three of these guys having competition between them, seeing who can outperform the others. Yep.. this could be a very fun season.