I've always had the opinion that people that know what they are doing use Opera or Firefox (or Safari if on Mac). The question of which one is better out of Opera or Fx (the abbrev. is not FF

) tends to simply be which one a person used first. Both are great browsers. Each has their own benefits and quirks. My days on the web went from Lynx > IBM Web Explorer > Netscape > Opera. Firefox was years off of being out when I started using Opera so that is what I became familiar with.
-MJ