I picked Horford, but if you put Smart on this poll then you need to pick Bradley. Avery Bradley is a FIRST team all defensive player (there's only 5 in the league!!) and he is a much better spot up shooter than Smart. He's also less likely to get thrown out of a game, flop, or generally lose his temper.
Bradley might have been better than Smart last year (possibly), but he has no chance of being our best player next year. At 25, he's past the age that players make huge improvements in their game, and last year he was not nearly as good as IT. He frankly didn't deserve to be 1st team all-defense, and offensively he's below-average at everything besides shooting. Still a nice player, but no star potential.
Plenty of players became better after 25. Lenoard and Teague are two perfect examples. I think AB will be our best 2 way player.
If you are referencing Kawhi Leonard, he is 24.
AB will mike slight improvements, but I dont see him leapfrogging Thomas and Horford.