After alternately using IE 7, Safari 3, Firefox 3 and Opera 9.5 for nearly a month, I can conclude that Firefox 3 is the best browser among them (at least on Windows and Mac OSX).
Firstly, a good browser should render web pages correctly and Firefox 3 gets 71 marks in acid3. I know, opera 9.5 gets 83 marks, Safari 3 gets 75 marks. But comparing to IE7’s 14 marks, I think 71 is acceptable…
Secondly, Firefox 3 has more functions available. I am not talking only the build-in functions, but including add-ons. Actually Opera had the most powerful build-in functions since a long time ago, but it is lacking add-ons, or I think the add-ons do not act like the way they should be… they act like separate applications. Also, for every Opera build-in functions, or nearly any functions you may think of, there exist a equal (or better) add-on in Firefox. (BTW, this one rules…)
Thirdly, Firefox is cross-platformed (Windows, Mac OSX, Linux). There is only a IE 5.2.3 on Mac, seems that there won’t be an updated version of IE for Mac soon. Safari for Windows is still young, most plug-ins for Safari work only on Mac. Only Opera can run on Windows, Mac OSX, Linux like Firefox.