Any K frame with a good tuning job.
I agree it is hard to get a good feel on a J, but I have put Wolff springs in all 3 of mine and they are improved, but not superb, and all just a little different frome each other. I have a 66 with a selected factory mainspring and a lighter trigger spring, that is about as good as it gets. Out of the box, I suppose then, the mid size frames with the smooth wide trigger. The large frames I have handled in .44 are pretty good, but you have alot more moving mass with the huge cylinder and the frame does not fit my hand as well. But then there is some variation in production guns so some guns just feel like gritty sand inside. I have not handled the guns with more than 6 shots, so I have no idea if the timing of the mech. feels different.