As you say, it is much a matter of personal preference. It depends on how you use the internet. I like Opera as I find it much faster than IE for what I do. I started this thread when 7.11 came out
Now vesion 7.21 is released and even better. click here My favourite plus points in order of priority.
1. Multiple Document Interface - many sites open at once. One click switch between them by means of the page tab. Makes it easy to copy and paste links, text, etc., when posting on forums.
2. Instant backtracking to previous/next pages. Very quick to browse to something read in an earlier thread before posting a reply.
3. Built-in email client. Database design is great but different to other email clients. I found it easy to get accustomed to. Email checking/notification while browsing doesn't interrupt, but you know when new mail has arrived.
4. Highly customisable. Arrange tool bars and menus any way you want. (Within reason) Skins too.
5. Built-in popup stopper and download manager.
6. Active forum to get help when you need it (~_~) and criticism when you don't. (>_<)