Mine (that I've seen so far) are:
XLR8 - seems pretty popular, and I agree that he's just plain cool
Fourarms - yeah I know he's a Machamp clone but that's ok with me
Cannonbolt - I think the comical scene of him trying to put out a fire by blowing on it sealed it for me
Spidermonkey - does whatever a Spidermonkey can :p
Diamondhead, XLR8, Upgrade, Wildvine, Way Big, Jetray, Goop, and Alien X! :D
-Ditto (the alien, not the Pokemon)
There's still a lot that I like, though.
Well, lets see:
Heatblast - An alien made out of fire. Whats not to love?
XLR8 - His design is pretty cool, and I dig the super speed.
Diamondhead - One of Ben's most used and powerful aliens.
Cannonbolt - I just love it. I love its concept.
Chromastone - Its like Diamondhead 2.0. But at the same time, not unoriginal.
Big Chill has really grown on me too. I love the way his wings fold around him to form a hood and cloak.
Ripjaws, I rather the old series!
Heatblast, Spidermonkey, Humongasuar, Big chill, and Diamond head
Swampfire. He's genius! You don't see a Grass-Fire type Pokemon, do you???????
Swampire and Big Chill!
I like Nanomech, Ghostfreak, Bivalvan, and Big Chill.