Two plugins I need, WOT and Xmarks do not work with Comodo Dragon, probably due to the fact that CD requires digital certificates to include complete info (such as an address). There is a workaround for Xmarks: Xmarks Options -> Advanced -> Encryption: No Encryption. This should allow XMarks to connect with the server and synchronize bookmarks but username & password will be unencrypted. There is no workaround for WOT as far as I know.
Opera has a great interface design and interesting features. Before Firefox was released it was my favorite browser. Today I find it a bit slower than the competition and some sites are not optimized for it.
Firefox, obviously the best feature is its plugin architecture. Unfortunately this is the reason why this browser starts slower than others. Browsing speed is great. The new FF 4 has a good interface.
Chrome/Iron Perfect interface, great speed, almost all the plugins I need.
I usually switch between FF 4 and Chrome.