There are poker pros in both limit and no-limit. Entirely different strategies employed when playing to win. I wouldn't say whether one is better than the other. Biggest game in the world was played with limit holdem (Beal vs Corporation). There are those who are much better in limit than in NL ie Harman, those who are better than in NL than limit ie Ungar, those who are great in both ie Ivey. Like trading, many ways in poker to play the game to win.
As in trading, you should be familiar with all styles to be well rounded. Lots of poker players cite boredom as a motivation to play a different style of poker.