My favorite Battle Beast (as predicted above) is the one I owned as a kid: Rubberneck Giraffe.
He has the coolest weapon, resembling a tree branch which is representative for nature and 'beasts' in general. Also he seems to be the tallest of the Battle Beasts, which stands to reason!
I was very disappointed in my fave once I saw he gets his butt kicked in the Transformers episode.