Speaking only of the FT airplanes I've built/flown personally ...
Sparrow: I think the Sparrow would be an excellent choice for ball-field flying. It flies amazing, handles wind really well, and can operate in tight places. Plus it's one of the quicker/simpler designs to put together. I had the airframe together in about an hour and the motor/electronics installed in about another hour.
Fokker DR-1: I was surprised that this airplane seemed to need more room than I expected for it's size. You can fly it in tight areas, but you have to be a bit careful to keep it in close. In my build I got the top wing slightly warped so it wants to pitch up and stall in right turns and wants to tuck under in left turns. I'm really bummed out about that ... I thought I was super careful lining everything up, and I put a lot of time into the finish and markings ... so it's more of a wall decoration for me right now.
Storch: I really love this airplane and design, but it is one of the bigger FT designs. I think you could easily fly it in a small space if you were careful, but it is a bigger plane that likes to range further if it can. I have an 8' telemaster senior (arf) and the storch flies so much like the big telemaster. I love it ... now I want to build an 8' (or 12'?) foamboard storch ... some day!