I like them all as long as they have a robust personality. Our little pug is a great guy, he's energetic and playful, and tears around the house and yard when he plays. You can "thump" on him and he loves it. He's a solid little dog. Of course, there is nothing like an 85lb GSD who can thump you back!
Watching a dog like that, the grace, strength, and intelligence he has makes that the kind of dog I really enjoy working with.