Browsers and webdesigners, it is an equation that collapses on itself.
IE is by far the most compatible browser. Firefox close second. After that compatibility is thrown out of window. Firefox can thank its second place for its popularity, the rest don't have that luxury, not even Safari.
IE6 was the no-frills basic browser with good compatibility but poor security. I guess IE7 improved on that while still attaining the top place in compatibility. I guess we'll see how things turn out when IE8 comes out. After all it is supposed to be highly standards compliant and uses new rendering engine. Perhaps compatibility of other browsers will also improve with this.
I loved Firefox because it was a fast, lightweight no-frills browser, just like IE but without the security issues. As years passed it got bulkier. While it is still my #1 browser, it just doesn't seem like the good old Firefox anymore. Thank god Firefox extensions are optional, as I don't use any of them.
Opera somehow never appealed to me, the interface always felt clunky and rendering slow. Well, it is still a good browser but seems to only appeal to the minority. Safari has pretty same problems as Opera. Slightly slower rendering and odd interface kinks. The rest even less used browsers I won't even go into.
Webdesigners, you either love or hate them. They are the ones who make the websites you visit, but they are also the ones who make their sites to work only on IE, Windows Media Player, etc, etc. So much for cross-platform compatibility.
There should be fourth option in the poll; Asparagus. I would have voted that.