Well I've got Safari on here but I don't think it's any faster than Firefox and in fact recently I was working in a place that had a few large Macs for graphics. None of them used Safari and in fact prefered Firefox.
That's not what I said though - I use Firefox both on my work laptop and my home Mac. As above I guess you could infer that I 'prefer' it. (In actual fact, it's because I'm a lazy so and so, and haven't got round to downloading Safari 4 yet - I'll remedy that right now)
What I was referring to above was the recent release of Safari 4 and that, by all accounts, is far quicker than both IE and Firefox.