i'm a major FF AND Opera fan... but i find there are pro's and con's to using each.
an interesting link, related to this subject:
FIREFOX MYTHShttp://www.webdevout.net/firefox_myths.php-
(the section on Security vulnerabilities, seems to make out that OPERA has the LEAST vulnerabilities. "The information was collected from Secunia, a leading computer software security monitoring company. This information was last updated August 25, 2006.")* here's a link on IE 7 still not supporting CSS satisfactorily:
http://www.windowsitpro.com/windowspaulthurrott/Article/ArticleID/47208/windowspaulthurrott_47208.html* This link:
http://www.webdevout.net/browser_support.phpis about how the browsers support web standards.
i don't know if it'll make alot of sense to people unfamiliar with HTML or CSS -- but, it helps explain why different browsers display the same page code in different ways.
ALSO: most developers design pages for IE, since it's the most popular browser. but SOME others take advantage of CSS functions that render in Opera or FF but NOT IE. and THOSE pages, are much more interesting to view in a browser capable of reproducing the effects.
(this is kind of a silly example, but it's all i can think of right now... the CSS pseudo-element ":after" is used by kids on myspace to change "joey has 28 friends" to "joey has 20
BILLION friends.")
just one dumb example, and i'm not an expert on this -- but i keep reading about the frustration developers have, wishing IE would implement more CSS / XHTML standards.