Boxers that in your opinion could have excelled in other weight divisions

Watching Raging Bull the other day, Jake was always complaining about his small hands, and how this would always stop him from being a heavyweight contender (I'm not sure if this happened in real life or was inserted into the script?)

So I wanted to get some opinions:

Which fighters could have excelled in another weight division, but never made the move?

If you can include which division, and why you think they would still be competitive.