I play both .5-1 Limit Full Ring (graduating to 1-2 soon) and 25maxNL Full Ring

Limit is clealy not as exciting and requires you to read a book or two (Winning Low Limit Hold'em by Lee Jones and then Small Stakes Hold 'em my Milller/Sklanksy/Malmuth). Playing ABC poker at mico limits (big bet $1 or less) is easily profitable as long as you follow the road map. After you get your feet under you you'll be on your way to try alternating your play. It's a slow grind, but if you're patient you'll learn solid poker (position, betting for information/value, starting hand requirements, etc.) while playing a lot more hands than you can at the low buyin NL tables as a profitable TAGG camper (arguably the best style in these highly loose games)

No Limit is certainly more exciting but if you're not already established as a disciplined poker player/bankroll manager it's a riskier learning curve. I think a lot of people start playing NL increase their Bankroll fast and never look back. But there are certainly even more who see their bankroll disappear over a few days overplaying/gambling with their stacks.

I still feel the safest way to learn the fundamentals of poker is reading one of the above mentioned books, play micro limits profitably for a few months, build your roll and then dabble with both sides of the cash games. Basically it comes down to your preference, but by no means are you grounded in one game for the rest of your poker career by the choice you make now Good luck