I'm a very competitive person.So I use the character I like the most I can. If I start to think he is slowing me down, I try someone else that I like, at least, the playstyle.
In Braw, Pit and Metanight were my first and second pick at the game. I just like them.
I had no idea of the competitive scene at that time, but I liked MK voice and think he is stylish, so I start to playing him. At a point, I start to look at the competitive scene and was happy to play the most powerfull character, until he got banned.
I returned to play Pit, who I liked almos the same and he is my Brawl main until now.
But when I started to have problems with some Pit MU's, I returned to train my MK (now unbanned).
I'm used to play with Pit almost every single game, but if I know I will be in disadvantage, I pick MK with no regrets.
Its play to win, if you play in a competitive scenario.
In SSB4 , I'm playing mostly Pit too.
But I like Mario and Sheik combo-ish playstyle, and pick MK and Ike to train sometimes too.
I'm thinking I will main Pit with a secondary top tier (who I like, like Sheik) again to erase the bad MU problems.
Hate me , but that's my choice