I'd have to say Carp.Most fish give up after a few tugs, but carp fight you right to the end.I had one on last year that had to be over 30 lbs.I fought it for 20 minutes until it broke me off. River smallmouth are great fighters for their size.Even the little ones put up a good fight.
depending on your gear, i'd have to say #! carp, #2 channel cats #3 iceout lakers grump