I forgot to do one yesterday, so I'm doing another today. Hopefully, this will be the last time something like this happens.
I don't think I have a favorite Animagus. We don't across many in the story--James Potter, Sirius Black, Peter Pettigrew, Minerva McGonagall, and Rita Skeeter.
Well, I think I like Sirius's Animagus form the best, because I love dogs. He's a big black dog, one that resembles the Grim, but it's still a dog and it's cool.