When I was reading the question of this user, I got a strong feeling that he was searching for some features and improvements, not for replacements. Firefox and opera do have advantages (I used them both) and disadvantages. Did you get Microsoft Update working in these browsers?

Anyway, when my goal is to suggest REAL replacements, then I would strongly suggest to install freeBSD as operating system and KDE or Gnome as Windows shell. There you go!