i've fished grand lake and indian a lot. grand is definately best for cats in my opinion. Never seena flat come out of there tho, not saying it hasn't, i just haven't seen it. I've heard of a decent blue and channel now and then, but mostly a ton of eater fish. Soon as ice is off I'll be back home in Lima and heading down there to try a few of my places.
Fish the auglaize in wapak below the dam at night. People dont realize just how many cat are in there. Few weeks back i landed an almost 21# channel on chicken liver.Catch a lot on cut blue gill also. Also theres quite a few flatheads there if you can get past all the snappers.They range anywhere from 5# to 18#.Use green sunfish,rock bass and shiners. I fish there almost every day.Get with me and ill show you how we do it here