It's a little about your stroke, but equally about the conditions you play on. Easier to hit a 3° bounce wedge off of very tight lies than an 8° or 12° bounce. In fluffy soft lies, the extra bounce guards against slightly fat shots, in theory.
Bounce essentially raises the leading edge off the ground for a neutral strike (club shaft perpendicular to the ground at impact.) Also, delofting the club "subtracts" bounce since your leaning the leading edge over closer to the ground.
8° bounce is middle-of-the-road, and what I'd choose if I didn't have a compelling reason to go one way or the other. Also, your sand wedge probably has a LOT of bounce, more like 12°, so you don't need another wedge like that in your bag.
If you want to be able to hit higher pitch shots off of tighter lies, the 3° bounce would be a little easier in theory.