Please provide a link to a better alternative. I'm interested in Impulse but its nice having all my games in Steam and I'm willing to spend a few extra bucks.
I'd say gog.com is my personal next best alternative (strictly speaking experience wise).
However, I don't think gog.com's current model would work well for games that need to be updated frequently as they don't have an easy update program or the like.
I use Steam as well, but I wish Steam was more like GOG.
In particular, I find it really heinous that Valve allows publishers to add their own DRM on top of the DRM that Steam already provides. (e.g. games that use SecuROM in addition to Steam) That's something Valve could require publishers not do, but they'd rather have the money