Kowalski
I was originally disappointed that the original actors from the tv series weren't asked to voice the penguins.
In the end I actually didn't mind all the voices, they did a great job...except Kowalski. In the TV show his arrogant dramatic academic voice was the perfect contrast to Skipper's macho meathead.
In the movie Kowalski sounds almost like a frat boy, doesn't stand out, and his jokes just fall flat as a result. Missed opportunity.