Fire - has the most overall damage due to massive AoE's and the scourge effects of Rain of Fire.
A normal corruptor attack chain:
Fireball
Fire Breath
Rain of Fire and clean up whatever still is twitching
Rad - has a powerful -def to use against hard targets but not as solo friendly as fire or energy.
Energy - is fine but more single target oriented. Few AoE attacks and Knockback which can make it tricky to use with many of the secondaries.
Secondaries:
Dark is great with Fire and Rad and if you are patient and open with torrent and THEN tarpatch your enemies will be on there backs and debuffed with Energy.
Kinetics is good with all 3 best with Fire as the AoE's are nice once Fulcrum shifted.
Cold or Thermal is good with all 3.
Storm if you use it wisely can be good with Fire and Rad but tricky with Energy.
ok thanks for the reply and tips :-)
i've been looking at some powersets not sure what would be good
was thinking either fire,rad,energy not sure what the pros/cons are for each and what are really good secondarys for these.