Until recently Google Chrome and Safari 5 outperformed the latest versions of Internet Explorer (8) and Firefox (3.6). Now the recent releases of Firefox 4 and Internet Explorer 9, both compare to Chrome and Safari. Benchmarks show some difference, but when using them there is little noticable difference between Firefox 4, Google Chrome 10, Internet Explorer 9 (32-bit) and Safari 5.
Google Chrome is a nice, fast browser. I like the Chrome Apps (especially the ability to run TweetDeck inside Chrome on a usb flash drive). Another good thing about Chrome is the way it automatically and silently handles updating itself. Before Firefox 4 RC came out, I was starting to use Chrome more because of it's faster speed. The biggest problem I have with Chrome, is the inability to do Print Preview and Page Scaling. It may not seem like a big deal to you, but many websites are not printer friendly, and may waste a lot of paper if printed blindly. Without the ability to Print Preview, I will not print from Chrome. Page Scaling is a nice feature that again both Internet Explorer and Firefox have, but it's not as vital as Print Preview.
Internet Explorer 9 is defintely an improvement compared to Internet Explorer 8. The main reason I moved away from Internet Explorer in the first place was because I was concerned about more vulnerabilities due to it's integration into the windows operating system. Internet Explorer 9 is still Internet Explorer, and it's still integrated into the operating system. Also, Internet Explorer 9 requires at least Windows Vista!
Safari 5 is a good browser. The windows version doesn't allow Print Preview or Page Scaling as mentioned above under Google Chrome (I'm not sure about the Mac version).
Last, but not least: Firefox 4 ROCKS! Firefox has been my favorite browser since version 1.0.6, and Firefox 4 is the huge performance improvement that Firefox needed to compete with the speed of Safari 5 and Google Chrome. Firefox 4 also has significant security improvents. (Full list of features)
My recommendation remains Firefox, but Chrome and Safari are also good browsers. The choice is yours, but I highly recommend using one of these four browser versions because they are the fastest, and they offer more support for the newer HTML5 and CSS3 standards.
If you are running Windows XP, you should definitely try Firefox 4 or Google Chrome since you cannot update to Internet Explorer 9.
If you'd like to benchmark these browsers on your own computer, try Peacekeeper.
Oh, and if you're using Windows 98 or earlier, it's time for a new computer!