The beta of Titanfall (AKA, my first impressions; not much changed on release) was some of the most fun I had with any game, all year.
I also bought it on release.
But I quickly lost interest. Why? Titanfall *was* a lot of fun, but it just doesn't have staying power.
I actually like Origin more than Steam at this point, so that didn't influence me, at least.
...Though the 50GB install did. I was running a 240GB SSD in my PC for much of the year, and a 50GB game needed to be pretty damn good to make the cut there. But once I upgraded, I still didn't really feel like going back.