My vote goes to Talonflame. Aegislash is nice, but he's fairly easy to deal with, provided your prediction is good. As for Talonflame, it's nearly impossible to revenge kill due to its insane speed and priority Brave Bird, and walling it is difficult due to the high base power of its STAB moves and access to boosting through Swords Dance or Bulk Up. Even with Stealth Rocks up, it can usually kill at least one thing before it goes down. Aegislash at +2 is dangerous; Talonflame at +2 is nearly unstoppable.