Who do I pick?
Pick whoever you want.
Character choice is obviously important, but sticking with someone you like is far more sustainable than taking an early tier list as gospel. Modern Fighting Games are as such that it's nigh impossible to lose on character select, and more importantly: Character strength is relative to the highest level of play.
Hop in game and experiment. Even if Street Fighter 6 is your very first fighting game, you might already have an idea of what type of character you're looking for.