How about this for a possibility?:
Heavyweights- Galactus, Celestials, Living Tribunal, and other titanically powerful cosmic beings of that caliber.
Lightheavyweights- Wonderman,Thor, Silver Surfer, Sentry, Hulk, Juggernaut, Iron Man, Hercules, etc...(notice these are all at least class 100 superhuman strength). Also, Dr. Strange would be considered a part of this group because of his powerful magical abilities.
Middleweights-Colossus, Thing, Ms. Marvel, Submariner, Firelord (notice that being cosmically powered does not automatically a heavyweight make), Hyperion, Ares, Vision, She-Hulk,etc...
Lightmiddleweights- Spider-Man, Luke Cage, Iron Fist,etc...
Lightweigts- Daredevil, Spider-Woman, Black Widow, Wasp, Captain America, Punisher, etc...
Of course, this list is by no means comprehensive, but its, generally, my opinion...