The SEOBook Toolbar seems to work best on FireFox 3 and includes as much data as you could ever need to evaluate a page quickly. Best of all it has an in-built RSS reader with the Blogstorm feed included meaning I get lots more RSS subscribers which is why I decided to help Aaron promote it. 😀
Last year I switched to Google Chrome and don’t use Firefox much at all. Chrome is faster and allows me to get more done in a day. The disadvantage is the lack of toolbars although Dave Naylor has an overlay bookmarklet that does enough for me.
Do you use SEO toolbars? Which is your favourite?