The Rays had the best pitching in the league last year, even after adjusting for their park. The defense helps out a lot, sure, but it'll be great this year too. Shields was good, but they have the arms to replace him. Cobb, Archer, Fauxto. They'll cobble together a 5th starter. And Hellickson has a 2.96 ERA in 64 career starts. At some point you need to look at the results instead of using estimators. He's not the 4.5 ERA guy his xFIP suggests.
Their offense is also not nearly as bad as it seems based on their run totals. The aforementioned park does a lot to suppress them. By wRC+ they were a top 5 offense last year. Having Longoria for a full season would go a long way to maintaining that. With the best rotation and one of the best bullpens in the league, they could easily win the division with a middle of the pack offense.
But of course, I picked the Jays. If they have luck with health I think they're the best team pretty clearly. There are lots of injury concerns though with JJ, Morrow, Santos, Janssen, Bautista and Lawrie. Will Edwin repeat? Is Melky off the PEDs? Is Rasmus ready to contribute? Will Romero work his way up from High-A ball any time? So many questions, but the amount of talent is so immense that I can't bring myself to vote for another team.