I actually do most of my debugging in IE now - and I've actually come to like the devkit they've got going. Ok, I am developing for internal intranets which of which my primary is IE, but they've actually come a long way. In terms of PC browsers (Mac is a different story) I'd probably put Chrome first, IE second and Firefox third.

I still prefer Chrome, but partly because it is my preferred browser on Mac too - I like consistency. I also think that their devkit is ever so slightly better... but in saying that I'm not unhappy with IE - it does what I tell it to do, it's fairly consistent and feels quite light (compared to Firefox which still feels heavy to me even after their improvements...). Admittedly there are some tricks you need to learn in the IE devkit (e.g. add an attribute of style to create new CSS definitions) but all in all I think they've done a pretty good job at cleaning up their act!

PS: I used to do ALL my development in Firefox with Firebug and the Webdev kit. I find now that Chrome/IE handles things very well: though Chrome still allows me to install the Webdev kit if I need it (e.g. rulers, security checks etc). I guess I switch browser camps often based on my needs :)