I’m using Exposè, but it is so much less convenient than alt-tab: try this on a laptop and follow carefully how much your hands have to move away from the keyboard.
I try to avoid installing third-party apps that modify the default behaviour of key elements as the Finder because they add instability (and this machine already crashed too many times). Let alone pay $15 for something that should be there for free. No, thanks: I’ve already paid extra bucks to get a Mac (not me, the company). 🙂