Terra was BBS hard mode but he was fun. You just need to learn the best times to dodge attacks, it feels a lot more like a real action game with Terra than with Ven or Aqua (where you spin2win). Of course, you don't have to abuse dodge rolls for those characters since Shotlock abuse is equally OP.
And drive forms (aside from early use of Brave/Wisdom) were just fun to use when fucking around and farming. Generally the problem is that you rarely ever needed the extra power drives give you in fights, but if you just want to style on motherfuckers they're awesome. Bouncing around casting Thundaga and watching shit blow up is the best. Master Form got too much style.