I loved Inception, however when I watched Social Network, I was blown away. I watched it again a week later because I couldn't believe how great it was. I also have to say I found the scoring in Social Network fantastic, I couldn't get it out of my head (especially the main theme music right after the debate Mark Zuckerberg had with Erica Albright), and while the twins were rowing in competition. Ohh and Sean-a-thon "A million dollars isn't cool, you know what's cool?" "You?" "A billion dollars."
Inception is very good too, but I find the script is not as tight, the dialogue not as interesting and the acting not as good as Social Network.