I'll eat just about any fish depends on my mood and the water I'm fishing. Take for example I love fishing for smallies in local small rivers and streams. Where they can get to a decent size, but bigger ones are few and far between usually. They don't reproduce or grow really fast in these rivers or streams so I when fishing for smallies I let them go around here. Now if I catch a spotted(kentucky bass) in these same waters it gets kept as they are known to not grow as large as smallies will in rivers, and they compete for the same food. That and they don't fight as well, and I don't have a problem keeping a lesser desired species to try and help out the species I'd rather see. Catfish when I go catfishing I'm usually out to try and stock up the freezer. With that said I follow the regs, but if I get a big one I get a picture and let it go. Too much wasted meat on the big ones as they have a lot more fatty red meat/yellowish meat that doesn't taste so great. So if the catfish if they are getting over the 30" mark I let them go to get bigger and reproduce more. For eating I like the smaller couple pound catfish they are abundant I get good fillets off them, and they taste great. When I'm pan fishing I'm usually after fillets, so very few crappy or gills get thrown back if they are of decent size. But I don't think I've ever kept a gill or crappie limit as I usually don't feel like cleaning that many little fish. When I sauger/walleye jig on the ohio very few get released they are tasty.
But when I lived in michigan for a short while I would keep smallies up there as they very abundant and even hated by many walleye fisherman up there, which seemed like that's what everyone up there was after. Heck up there they called white bass silver bass and hate them. I kept loads of them and every guy back at the ramp thought something was wrong with me for keeping them, and smallies. They usually just pissed the walleye guys off as they would catch lots of smallies, and white bass when they were after walleye. But I didn't always keep smallies up there or a limit for that matter just when I felt like having fish or wanted some more to put in the freezer. Just depends I like to practice conservation, but also like to eat fish so I try to make it a balance of both.