I've had a nice range in sizes. From...
Shadow at 95 lbs, Jack 45lbs, Micki and Mini are 20ish lbs, Kyra 10 lbs


And from my experience, I've found that I like Jack's size the best. He's small enough to be a lag dog and fit lots of places, but he's sturdy enough that we can play rough. And in agility he's just under 20 inches tall so he only jumps 16, which in my opinion is the best class to be in.

So, I like 'em medium sized!