Fave: Karhu, obviously. The avatar says it all. The bears have been due a quick, jumping cavalry heavy, and while the primary config is more fun than useful, the alternate configs are brutal. After that, the Bruin is a nice Assault version of my favorite mech, the Grizzly. It's an Assault capable of bullying virtually anything below 80 tons, and throwing enough damage downrange with enough mobility to act as a good heavy harasser for slower assault mechs.