Cash games are a better way to build a bankroll in my opinion because you're more consistently and immediately rewarded for making correct decisions. You can make a lot of good decisions for a long time in SNG's or MTT's but still have your bubble burst or get eliminated before you get a decent win. Tournaments often devolve into coin flips and you have to come out ahead in many of those spots to do well. In a cash game, every time you win a flip, you win. Every time you lose a flip, you lose. It's not a culmination of many of those marginal spots equaling one big win or loss. Plus, with cash games, there is no pressure to even get in a coin flip to begin with. If there is a fish @ your table and you feel like you're pushing a 55% edge in one situation, you can often just fold or wait for a better spot when your edge is higher or you have him drawing dead. This is a very powerful tool for building up your bankroll.

Don't get me wrong, though, tournaments are fun and I got my start in SNG's and did pretty well at them even struggling with cash myself in the beginning. But, after a while, I realized that tournaments are a novelty in terms of making cash. Even Dan Harrington recently did an interview and said that the best way to make money is through cash games. They recommend you have like 100 buy-ins for any MTT that you enter because the variance can get so high.

Surviva316 makes a good point, too. You really learn the game by playing cash. You don't look for spots to push all-in because your stack is low. You're not pressured to play trash because the blinds are about to go up. There's brief periods in tournaments @ the beginning where you can play real poker, but cash games are ALWAYS in that moment.

So, if you REALLY like tournaments, you should probably play them because poker SHOULD be fun. On the other hand, if you want to make a lot of money and get good @ poker, cash games are the pure way to go in my opinion and I find them very fun. Whichever you choose, you can still sprinkle in some of the other one for fun, but I think it's best early on to stick with one game to try to get good @ it.

Good luck.