Blaziken! He's epic! And with his hidden ability then nothing can go wrong. Go with Blaziken, he's fast thank to his hidden ability (Speed Boost) and if he doesn't outspeed it's opponent (He can take two or three hits) he'll do it the next round. He's an excellent sweeper, his Atk and S.Atk is rather high, so a Flamethrower there and a Blaze Kick there depending on the opponent.
I'd go with Blaziken with his epic Mega evolution that raises his Atk, S.Atk AND his Speed. He'll be a deadly opponent, only four weaknessess, even though Chandelure also has four depending on his ability, but I'd go with Blaziken, because he has better overall stats than Chandelure.
If you want sources on them here they are.