IE 9 which is the best so far of all the IE browsers. When I need to have two browsers up at once so I can work faster, I have Firefox 4 which is not as fast. I also have Safari just to check with at times. Have also used opera and some of the others, but since a lot of pages are still desgned for IE, it makes more sense to use IE. Rememer that in IE- 9 under tools, you can click on F12 Developer Tools and then choose to use IE-7, IE 8, or combinations of all three depending on whether you want to change your browser mode and or your document mode.
Viejo