I don't have any idea which is easiest. I have flown several different types and they usually did what the pilot told them to do. The Pawnee was probably easier than the PA-18-180 in strong cross winds but was limited by wingtip clearance.
The Aeronca 11BC Chief that I owned in partnership, and in which I checked out all my partners, stood out as being one of the least forgiving. It would far rather go backwards than forwards. Having no brakes on the right side didn't help.
Current favorite is the FX-3 Carbon Cub but I hope my type list hasn't hit its limit yet.
(I don't think I have landed on grass since 1984 - 7-GCBC at Thruxton. All recent tailwheel time is on dirt/gravel or paved runways)