So I just pulled a Superior Iron Man from my first 5-Star Crystal.... yay. Was one off a Gwenpool and the crystal just wouldn't spin

I know that Iron Man is a waste of time to rank up, but I have heard people say that the "Superior" version of him is a little bit better (not by much but still).
Just wanted to know if there is any difference between the two, and considering he's my first 5-Star, should I rank him up even if he sucks?
I also got a Medusa from the 1 dollar crystal, and Ghost Rider from a 4-Star Crystal I opened shortly after. I know that both are good champions, but I don't actually know
why. If anyone could shed some light on these two characters and the best way to play them as well I'd appreciate it.
Thanks!