I’m sticking with the ‘fox. The “top sites” is better than an about:blank homepage, but the Speeddial add-on (Firefox) lets you do the same, and also select what the thumbnail is of. This is great because I never need to load twitter: I can see the newest 10 tweets from the thumbnail. Similarly, I have one thumbnail with the most important part of the weather forecast.
Tabs up top are sexy, though. Chrome beats out Safari in a lot of ways, however: faster java rendering (the fastest web browser ever? really?), threaded processes, sexier. Firefox outclasses it with add-ons, and what I believe to be the best address bar in any browser due to search keywords. It blows Chrome’s integrated search out of the water.