Woodhaven brand diaphram calls are what I use. They fit my mouth and I have been able to call fairly well with their construction. I have also use HS Strut brand diaphram calls. Some of the others just do not fit my mouth as well. I do find a V-Cut, double reed a very versitile call.
I whole heartedly agree with AJ Hare's point about sounding "close". No doubt that the call does need to be close, made at the opportune time, and not over done but certainly not exact .... look at it his way, I figure that no hen sounds exactly like any other hen, so maybe I sound OK. Lord knows that if it had to be "perfect", I'd never have had a chance to call a Tom in close enough for a shot.