I prefer Blaziken above all the others because of it's ability Speed Boost, has a Mega Evolution (thus greater stats) and a nice movepool, having access to many neat moves.
-It’s ability Speed Boost is nice when Swords Dance is used, meaning more Atk & Spe.
-Access to great movepool of High Jump Kick, Brave Bird, and Flare Blitz
-Could be a strong physical sweeper or a special sweeper due to it's mixed stats of Atk and Sp. Atk, although Atk is a little higher.
-Gains a Mega Evolution while the other two (Infernape and Emboar) don't have one, which means that Blaziken gets a stat boost.
-Defensive stat isn’t too good, but it becomes more decent after Mega Evolution.
This is why Blaziken is probably better, because Infernape's mediocre speed and other things, aren't as good as Blaziken's stats, while Emboar has pros, all of them are also to Infernape and Blaziken, while not very good defensive stats. As mentioned above, Blaziken has also Baton Pass to other teammates and they get awesome stat boosts, with an added bonus if they're mostly a physical attacker.
Due to all these circumstances, Blaziken is probably the best answer.