I voted for Safari. I have used Safari ever since version 1.0 (when I bought my Mac 2 years ago). I just like the simplicity of it and also it appears to display the pages the best of all the free browsers.
I don't really have any compatibility issues but I just wish that the odd thing would get updated, like allowing you to choose which search engine to use, rather than just Google. While I do use Google, I feel that this aspect is as anti-competitve as Microsoft usually is. And IE7, I believe, will have a search field with the ability to choose (not just MSN search
)
Also, I had to install Taboo to stop myself closing windows with multiple tabs by accident. This ought to be an option in the preferences.
The only other browser that I remotely like on Mac OS X is the new updated Camino 1.0 beta, which is very close to Safari anyway. It has a nice look to it and works essentially like Safari. But I still don't think it looks
quite as good when displaying buttons, widgets and just normal text.
I don't use FireFox on the Mac because it is a bad Windows port and it seems rather slow. It may be customisable, but I like the look of Safari, thankyouverymuch.