Camino. I'm all old-fashioned and whatnot so I don't use RSS feeds and all that fancy hoopla, I'm just waiting for the stable version that'll utilize spellcheck. (I miss that about Safari, oh, and the pop-up dictionary, too.)
there are many dictionary extensions for firefox2, and they are easier to use than safari's
such as:
https://addons.mozilla.org/firefox/1171/

and
https://addons.mozilla.org/firefox/2830/
