Opera
1. Absolute freedom with the interface, you can move/remove/add any toolbar, any icon, any button anywhere.
2. Integrated mail client. High quality, full support
3. Opera link - integrated synchronization/back up service. Never ever lose your notes, speeddial, bookmarks, ad block(urlfilter.ini),...
4. Great looking with glass-transparent skin when you have aero OS. No other browser can have transparent speed dial and it looks fucking cool
5. Fast, always has been, always will be
6. Loads of integrated features that you don't have to manually install as addons, mouse gestures, speed dial, using user javascripts(native grease monkey),...
7. Biggest number of options/preferences from all browsers. If you are not retard you can set anything in opera. It looks simple at first glance but its deep. It has natively more options than all other major browsers combined