Which business would you want?

None. There are plenty of games that simulate businesses, and they generally do a better job at it because it's the only point of the game. Every time they create some sort of business for Sims to run, all I hear about is the bugs. Sims are too multi-faceted to behave properly in a business simulation, and people get frustrated because the NPCs (or their own Sims) aren't doing what they're supposed to do.

Then again, the work aspect is probably my least favourite part of the Sims - my Sims usually don't have proper jobs. Work is the last thing I want to think about when I sit down to relax and play with my Sims.