oh gosh, it's really hard to choose one...so I'll cheat and give you a few, hehe. I love Rex, with the goofy little walk, and Luna! big squish! (I imagine she makes whale sounds)
also Juice, who I got shortly after Luna and just... you know. <3
I also adore Fungoomi and Sol, and, and..... ok, I'll stop. :p
here is a screenshot I took of my allstar trio - thank you again, such a lovely little game!