Wow! You're really putting me on the spot and likely to start wars!

Here's my view for what it's worth.

IE is a web developers worst nightmare. There's just too much that doesn't work and too many standards that Microsoft have totally ignored in a futile attempt to lock the browser market.

Firefox was for many years my browser of choice. I still use it as my primary development browser, simply because there are such good plug-ins to help the process and make my life easier. It was once a lean, fast browser for which we all have a great debt to pay. As it was primarily Firefox that caused Microsoft to to grudgingly start to redevelop IE, as it had fallen way behind (and still is). Sadly, Firefox has ended up almost as bloated as IE and personally, I think it's lost its edge.

Chrome is undoubtedly fast and generally good, but does have some strange behaviours on occasions. It can be particularly cantankerous when trying to run javascript on a development site (on a local machine).

Undoubtedly, Opera is the most underrated browser at present and I love it. It's stable, pretty much standards compliant and is generally the first browser I use to test a new site after initial development in Firefox (for the reasons I've given). If a site works well in Opera, then generally it's OK in Firefox, Chrome and Safari. So you only end up rebuilding it for IE!

Safari renders nicely, but is slow. Though I have to say, I don't have an up-to-date version, so it may have improved.

The problem is, in spite of EU declarations, many people still only know IE as the thing you get on the Internet with. It's different here, because you're talking to (at the very least) people who have a strong interest in computers and who are on the whole knowledgeable. The average computer user, isn't.