They're just very different in execution. I personally prefer playing with and against offense. I don't like battles taking forever. I don't like the lack of risk-taking inherent in stall. While I recognize that stall is a great playstyle, I think offense has a higher degree of difficulty but also a higher ceiling. I believe that an extremely well-built offensive team that is expertly played will beat the stall team with those same conditions most of the time, mostly because stall surrenders a lot of the initiative early in battles (unless people let hazards get up quickly in which case they're cooked).
Also, stall is mostly the same every time. You set up some hazards. You prevent Rapid Spin from screwing you. You stall some. You stall some more, shuffle around the damage, and throw in a little status. The formula is pretty much the same.
I think offense can be approached with a little more flexibility and creativity. For example, I remember using a Sleep Powder/EQ/HP Fire/Sludge Bomb Venusaur in Gen 4 that was a total baller (75% of the time...) and lured in a lot of unsuspected Scizors and Forrys. Not to mention non Shuca Tran. Even if you use lesser Pokemon in stall, I feel like there isn't the same thrill of luring stuff.
As much as it pains me, I've accepted stall as a playstyle. But offense is more fun, in my opinion.
YOLO