I like them all, but my vote goes to Oshawott.
Why Oshawott? I've been loving this guy since seeing him in the anime with his cute expressions (he's voiced by the great Lisa Ortiz) and his toughness with that scalchop of his.
I'm playing Black next month and I am choosing him as my starter!
Ever since I first saw him, I decided he was going to be my starter (and even more definite after seeing his cute face in the anime) cos I often chose Water-types and he is just as cute as Piplup was.
My profile is even colored blue and my avatar and signature are adorned with Oshawott! I just love him, you can't beat his cute face when you see him.