I've tried each of the main browsers (Firefox, Safari, Chrome, Opera).
I found Firefox to be the best of all of them. I live off bookmark keywords, keyword searches, and the Awesome Bar. Not to mention all of the other customization options.
I was actually a little disappointed with Safari. Even with Glims installed, it was still missing a few critical features. I can't assign a keyword to a bookmark, and the address bar search is weak. I can only search page URLs, and I couldn't search within URLs (I can't type "oogle" and see Google in the results.
Chrome has bookmark keywords and search keywords. However, it still doesn't have that same level of customization as Firefox (no about:config to play with).
I found Opera's interface a bit too cluttered, and it doesn't support one of the add-ons I need for browsing.