I use Chrome. Mainly because you can edit ANY bookmark by right-clicking. Can't do this in Safari or Firefox- the latter seems strange since you can do it in Firefox for Windows. Firefox feels much more clunky on OS X, while Safari and Chrome operate very bouncy and "Mac-like"...but from a configurability perspective, all OS X browsers seem inferior to Windows counterparts.
Now if Safari would allow you to edit bookmarks on the fly, it would be a cinch - Safari all the way. It's a cool browser.