I'm not installing Opera this time. I've been an Opera bigot for a long time, but it's not going on my primary work PC. I'm using FireFox 2 instead of Opera. Why? Three words: Google Browser Sync. The best description of Browser Sync comes from Google:
Google Browser Sync for Firefox is an extension that continuously synchronizes your browser settings – including bookmarks, history, persistent cookies, and saved passwords – across your computers. It also allows you to restore open tabs and windows across different machines and browser sessions
After having to rebuild my PC twice now in the last month, I'm tired of losing bookmarks and other settings. With Google Browser Sync, my bookmarks are synched up across machines. It adds so much value to me, that I'm giving up the faster performance, the better security, and the smaller footprint of Opera. Of course, I'm going to make Firefox behave like Opera as much as possible.