I'll say the Piper Cherokee. You're already used to a trike gear plane, next step is trike low wing. High wing taildraggers are almost as easy to fly as your trainer. If you're interested in a Cub, play with it on the sim. There's really nothing to it. I'm telling you, go for the low wing. I'm self taught from a sim myself. Flew high wing trainer 9 times, now moved on to low wing T-28 with flaps and retracts. You can do it as long as you can do it on the sim without crashing. Sim to real life transitions about 90% in my opinion. Best to practice real life flying in very little wind. I got impatient yesterday and flew the T-28 for the first time in 11-15 mph crosswinds. Did three cycles on one pack, legs shaking like crazy, but very happy that the plane came home undamaged.