Opera since....damn, way, way back.  So far back I paid $35 to eliminate ads and get one on one customer support!  
So many features, like saving pages in one simple MHTML file.  I think only IE has this.  My search bar has Find in Page, Ebay, Amazon, and Wikipedia. Always right there. 
I'm talking about Opera 12 point something.  A few months ago they rolled out v.15, now 16.  Turns out it was a complete rewrite using the Chrome engine!  NOT Opera.  No features I love.  
Firefox is my secondary, a lot of nice plug ins.  But still not having what I love in Opera, like the save pages to MHTML....unless I've missed that.  Every try to save a page in Chrome?  Ha!