I play mainly cash, but have had a few final tables in small online tourneys - 3rd out of 619 was my best, I think. My hourly rate is way better at cash anyway, and I rarely have time give up a few hours to a tourney, but I do enjoy them.
The thinking is entirely different, and, yes, the emotional investment is much higher in a tourney because one serious error can take you out and the bubble must surely be the loneliest place in poker (or going down to a one-outer, maybe!).
While I build up my bankroll, though, it"s cash for me - once I hit a certain level I"ll probably play a tourney a week and see how things go, but I view tourney money as a bonus, and ring game money as the earn...