To be honest, I've never tried SM so far, though I guess I'll love it. But the problem is, S or M, I can't decide which side should I stand on. Well, I asked my guy about his choice, and he can't decide either! Okie... Then it may be a great idea that both of us play M...
Apparently, playing S could be more challenging than playing M. You dominate the process, so you have to think about how to make it more exciting. At least, your body moves much more than the one dominated. While the other doesn't need to play so hard. He or she can fully enjoy it with some proper reaction (sound, gesture, movement...).
However, being dominated could be suffering if you don't want to be dominated. Well, I know, it sounds ridiculous. But actually, this is the key point --- you want to control without big effort. Neither the power of controling nor the the right of enjoying with less effort do I want to give up. That's the reason that I've never tried SM I guess.
Guys, what about you? Are you S or M?