One of very few, and it's quite baffling. Origin is just barebone and has no features, and on top of that, doesn't even patch games. It's common knowledge that some Origin games don't always come fully patched, and stay that way until you manually patch it. DA2 was that way for me. And don't you need an internet connection to play Origin games? Which is not true for Steam, it has a perfectly functional offline mode.
Origin = Useless, annoying, bad layout, but no longer has the serious issues it used to have (generally speaking). There's no good reason for its existence.
Steam = Provides a lot for the player, but if you actually plan on browsing the community section then prepare for slowness. But all it does is make gaming 10x more convenient, and provides a lot of useful features. If you don't care about the features (have no friends to communicate to, don't care about community discussions, somehow don't use mods, don't take screenshots, etc) then just set it to auto-login and leave it out of your way.