Find a character you have a history with. It may be good memories or you may like the games they are from. Use them. Play them. Don't stop. You CAN play ANY character you dedicate yourself to. Do not quit them. Do not change mains.
All characters have weaknesses. You have to be willing to deal with those weaknesses and work through them. Don't just change because "Falcons recovery sucks". Because then you change to Jiggs and get Up smashed all day then quit again. Its an endless cycle. Pick one and save yourself the wasted time.
If you stick with the same character, it will be extremely hard. However in the long run, it will be beautiful. You give love to the character, they will give it back.
That's my emotional rant for the day. Good night.