Some people find NL better than Limit, some the other way round. If you like the psychology and make well-timed bluffs, then No Limit is the way to go.
However, if your leanings are more towards a mathematical style of play, then Limit is probably better.
Certain flaws can also make one more profitable than another. If you find yourself temped to call the river to keep someone honest, then skip No Limit, as that river bet will tend to be very expensive. If you're determined to see a lot of flops, then limit is definitely not for you (No Limit you could potentially still turn a profit if you play post-flop very well, but in Limit you won't make enough on hands you hit to make up for the loose pre-flop play, generally)... there are lots of other aspects.
I'm tending towards the idea that if you like the format of Limit, and like a mathematical style, then you should play Limit Omaha or Limit Omaha High/Low rather than Holdem - because lots of players seeing flops with bad hands increases the value of good starting hands, rather than decreasing them. For big bet games, Pot Limit Omaha (High/Low) and No Limit Holdem both have their merits.