*bulbagarden.net image removed*
This was a bit hard, but I went with the Staraptor line. That fierce, predatory look coupled with a patch of red, complementary grayscale, and awesome design made this Pokemon one of my favorite Sinnoh inhabitants.
The Pidgeot, Noctowl, and Swellow lines are all tied for second. The Pidgeot line is just classic, with their majestic trailing feathers. I love how the Noctowl line is more of a nocturnal species, not to mention their Psychic-type capabilities. And then I began with Hoenn, where the swift-tailed Swellow made its debut, where I've come quite accustomed to it.
The Unfezant line isn't that bad, but they come in third place for me... I dislike the coloration of male Unfezant. The female Unfezant's coloration is a bit better, but not enough to redeem the entire line. Tranquill, while it has a nice name, looks a bit weird... And Pidove disappointed me in the anime, so they're not as great as before... >_>