I would disagree, for me the measure of a browser is how sensitively it treats your mark-up and code both from the point of view of a user and a designer. Safari is a bit too forgiving, and while that's probably good for the end-user, I often find that certain mark up works in Safari fine, and then not in FF, or Opera, or IE or whatever, and then when I check the code I find that actually I've made mistakes or written invalid markup. If you use Safari as your main testing browser you'll find that it lets you get away with all sorts of things that other browsers won't tolerate, and that isn't in the spirit of web standards.
FireFox, however, is too bloated and slow and un-mac like. I would argue Camino is better, for example, for the average user. And Safari is clearly faster, and way more standards compliant than IE, so you can hardly put them in the same category.