Can anyone here tell me any limiting/overused sets? please?

In no particular order:

• Castle, Carrotus, Diamondus, Tubelectric (Very overused and fairly limiting)
• Medivo, Inferno, Damn (Limiting and underused)
• Any Agama set (Overused and limiting)
• Any Disguise set (Limiting and some are overused))
• Any Blade set made before Space (limiting yet overused)
• Windstorm Fortress/Odyssey (Overused but not limiting)
• Kansas (Limiting and underused)
• Omen Woods (Limiting and underused)
• War Torn (Limiting and underused)
• Mez01/02/03 (Limiting and 01/03 are overused, 02 is underused)
• ET's Planet 2 v3 (Limiting and overused)
• Rollercoaster Park (Limiting and never used as of yet)

Of course the list goes on for much longer than that, but these are just some examples I can think of off the top of my head right now.

what about colony beach, funky and jungle ? aren't they underused as well?

any tileset that has less than 20 tiles can't be used for much of a level. one example being Iron crown.

The jj2 tilesets that mortalspaz listed are a bit underused, but it's largely due to the fact, imo, that those tilesets were limiting, somewhat incomplete and/or plain bad, Colony and Beach being the biggest examples

CelL's jj1 letni tileset is another classic example of a badly-made tileset being overused by JCS newbies.