I've only used Origin to download free games, so no idea how well the games actually run. The Origin software runs quick though and I didn't have a problem with it. I don't really like how the library is on Origin. I mean it looks nice and you can make the titles are big or small as you want, but the library is side by side images.
I like Steam how everything is clean and consise when it comes to the libary. Everything is alphabetical order in a list to the side and when clicking on any game, it shows which of your friends have played it, achievements, and news about the game in the middle, and then on the right size it has a clean list of various links, from forums to the game, a manual if it has one, community guides, etc.
Even though Steam is DRM, if a game isn't Steam compatible, I usually don't purchase it because I like the service. All this and I mostly play on consoles, so I have 200 games on Steam I haven't played yet.