I currently play both and I prefer beach volleyball. I find that the sand is more challenging in that it's much harder to run and jump in, but it's also more forgiving to the knees, ankles, lower back, etc. I have very little fear of diving for a ball in the sand. Although the classic indoor six person volleyball game is much faster, I get less of a workout because there are five other people who I can depend on. It's just you and your partner covering your entire court in the traditional two person beach volleyball game, unless of course you're playing fours or sixes.

Either way, I'd rather play volleyball than any other sport. But when it comes down to indoor volleyball versus beach volleyball, BEACH VOLLEYBALL RULES!