While third-party browsers won't be able to compete with Safari on iOS due to the technical limitations, I still prefer Chrome on my iPhone because it ties in with my Google account, syncing everything for me. The loss in per-page performance is somewhat mitigated by the fact that I have to load fewer pages than before thanks to features such as Chrome to Mobile and syncing of tabs, bookmarks, and passwords.

Also, Chrome is so well designed for mobile as on my Galaxy Nexus that it is difficult to switch to any other browser. The way they handle tabs is the best I've seen. Incognito mode also offers an easy way to simulate a second browser session without switching to another browser app, something I as a web developer cannot live without.