Mine is Staraptor, even though I hated its screech in the previous gens. I loved using Close Combat to trash Rock and Ice types, and using U-Turn to get out of sticky situations in 4th gen. It's my favorite of the Normal/Flying dual types, though it is pretty frail. Braviary and Talonflame are cool too.
Yvetal is a really cool legendary, like Lugia, but with Dark typing. I also love Zapdos, and it was fun to use when I played FireRed.
Talonflame. It looks so cool, being an red peregrine with flame paintjob. Its design unifies birds of prey, illegal street racing and car mods, fire pokemon and of course meteors, what with it going all brave bird of your enemies behinds. Its the Vin Diesel of pokemon.