Who is the most powerful superhero?

Overall powers? I would guess Superman also, OP.

Physically strongest I would say The Hulk or Thor.

I'm not a comic book nerd.

With that disclaimer, I'd argue that there isn't a single "most powerful" superhero. It's more like Rock, Paper, Scissors, Lizard, Spock. For each superhero, there is one (or more) who are most susceptible to his particular power while being susceptible to someone else's particular power.

This sort of question is kryptonite to me.

This is hard to answer because comic book universes are very complex, existing for decades with reboots every couple of years and have so many different writers who crafted their own continuity. The superhero movies are watered down and simplified for the public. And let's not even get into Japanese comics where you have the heroes of Dragon Ball, One Punch Man and One Piece who have their own power scaling.