In general. I liked Colter Bay more, having stayed at both. On a side note(this won't affect you) but prior to entering the actual National Park(gated entrance), I had disconnected my toad so that when getting to Colter Bay CG I had easier driving of the MH. They person at the gate would not let me through as a single unit....I had to pull through the gate, hook my car back up to the MH in her view and drive off only to stop again 100 yards down the road to un hook again. Rules are Rules I guess!
Anyways...Have a Great time at both The Grand Teton's and Yellowstone.