After flying sport for over 40 years, I have build a lot of them, flown a ton of them, and have to say that the one plane that is in front is the Great Planes .60 size Super Sportster. It needs to be built as light as possible without sacrificing strength and power it with a .70 to .80 size four stroke, in other words not a heavy engine.
There are many that are similar, such as the Bruce Tharpe Venture 60, the Sig Four-Star 60, and the Goldberg Tiger 60. Those planes have longer wingspans, 70" or more, which is super for transitioning from a trainer to a low wing, but the longer wings limit the sport pattern abilities. Plenty of pilots remove a bay or two off of those long wings to make them fly like a Sportster. The Super Sportster only has a 61" wing, the wing is thick, fully symmetrical, the wing transitions at every speed, will not stall, and touch-n-goes and greased landings are really fun to do. The thick wing also works well with a 4-stroke which slows the plane down so you can enjoy super slow, controlled flight. Tower Hobbies still offers the kit. It is a bit of a builders kit in that it requires sanding and old school techniques to shape it, but it is so worth it.
Try one and it will always be in your hangar, no matter what else you fly. I feel like every flyer, no matter how advanced, needs a Sunday Flyer to fall back and just relax and shoot touch-n-goes as the sun goes down and the wind dies down.
Thanks for reading. FPhillips