I've got a bunch of Ader bells, because I used to sell them. I have used DD, Apollo, Powermax, and a number of others. Of these, the Ader and DD feel the best to me, and feel just about the same.
But, having had the chance on a couple of occasions to use AKC style bells, I feel like their is no comparison. This style of bell is definately way better for long sets. I would love to have some, and soon will. I am waiting, because there is soon to be a third company carrying the same bell that AKC and PB carry, and they are going to be cheaper than either one.