I have quarter minus and like the look. What I don't like is trying to remove tree debris from the gravel but this problem exists regardless of the size of the gravel, although the larger gravel is easier to blow debris out of. You can get better coverage per ton with 3/8" (140 sq ft/ton) than 1/2" (120 sq ft/ton). Quarter minus you get 150 sq ft/ton. It really depends on the look *you* like.

We have 3/8" in parts of our backyard and like the look. I also appreciate the fact that its not awful to walk on barefoot and the dogs don't seem to mind it.

I agree with Mary about the quarter minus, but between the 3/8" and 1/2" I would go with the 3/8". I feel that it looks more natural and is easier on the feet.