I LOVE my Nexus 4 (running on Straight Talk) and can't wait to upgrade to the Nexus 5. The Nexus 4 has been my single favorite Android smartphone EVER. And I've previously owned a host of Android smartphones. Most of them just didn't work as well as advertised. The Nexus 4 does. Previously I had a Galaxy Note, for example, which I absolutely hated. It had all kinds of lag and performance issues, and I really hated getting updates so slowly. It's camera was crappy, its keyboard worse. The only thing I liked about it was the big beautiful screen. However, the Nexus 4 has a beautiful (if smaller) screen, too, and WAY better performance. I will NEVER purchase a non-Nexus Android phone (unless they let me down sometime in the future). I've been tempted by some of the HTC's but ultimately dissuaded by the fact that they still take a while to get the latest and greatest Android updates.
LG and Nexus FTW.