Regarding characters: 48 characters is a lot. Right now, I've unlocked up to Ganondorf. My two mains right now are orange Kirby and red Lady Robin.
Kirby's always been my favorite Smash character, and I love that they added an orange skin for him. (Orange is [theoretically] my favorite color, and I always played yellow Kirby because he was closest to orange.)
I'm not sure why I originally started playing Robin, but I really like her moveset. It has a nice balance between ranged and melee moves (and I really like Arcfire). The "running out of mana" hasn't been a real problem for me, 'cause I try to avoid stale moves. But I still haven't quite figured out how to use her down-B or Final Smash.