Are we talking bouncing or ground looping?
Pawnee is one of the easiest tailwheel types for either in my view. Hard to get them to bounce or ground loop. I'd suggest that the monowheel version of the Europa is one of the more challenging ground loop types. The Cub/Super Cub also is easy to ground loop, as is the Stampe. Tiger Moths less so, because of the tailskid drag.
The Champ is a delight to land - hard to get a bounce from that excellent undercarriage, wheeras a clumsy landing in a Cub can bounce. So far I haven't ground looped a Champ, even in stiffish crosswinds, though I suspect it will be a easy to do as in a Cub.
A Pitts is a nightmare for potentialground looping, I thought. Though that feeling of being in a slightly out-of-control shopping trolley once you are in the ground roll keeps most folk on their toes (almost literally) !
Austers must be amongst the best bouncers in the business thanks to their bungees, though with such a heavy tail that ground looping is rarer.
Most motor gliders seemhard to ground loop and few will bounce much, though prop ground clearance can be an issue in a bad arrival.