I will preface this by saying, I do not consider myself a limit plaeyer. I have played limit, but I primarily pay NL. I think the the argument, which is more difficult, is a very difficult question to answer. You can profit at both, it's just done differently. You have idiots playing both games that have no idea what they are doing, and those are the idiots you profit from. Sometimes there are tables where you identify a player that might be as good as you, if not better. You try to avoid confrontation with that guy, unless it's cheap. You do both in both games.
Now, you can make more money off of a guy that overvalues his hand in NL, than in limit, for example, those dummies that play any ace. When they hit their ace and think it's good, and you have a better kicker, he might pay you off. The trick is, knowing how much he's willing to pay. If he tries to go all in and you call with AK, you'll take his stack. In limit, you can make the same read, but you're restricted to how much you can get out of him at that particular time, you can only raise so much. It takes away the decision you make as to how much to bet to bring him along without betting him out of the pot, or, if you can induce a bluff, what size bet will get him to do that so you can break him, you just can't break a guy in one hand in limit, unless he's already short-stacked and hasn't reloaded. Then again, you get those idiots in NL who put half their stack in pre-flop heads up with something like suited connectors or any two cards (they were suited after all) and suck out when you raised with a monster. You have to know your opponent and know how he plays to avoid being sucked out on like that. I prefer NL because, for me, it provides me a better opportunity to exploit bad players and take advantage of it to the fullest.