Because I develop Web sites, it is necessary to test them in the most popular Web browsers. This gives me a fairly broad perspective and I'd like to share my impressions of some major browsers.
Internet Explorer - IE is a good browser in terms of the user experience and it is the browser I use most often. It is also the most hated browser amongst Web developers for its peculiar historical take on Web standards. IE8 finally addresses those concerns. We developers will hate it less (and maybe even like it) while users will continue to make it the most popular.
Firefox - For Web developers, Firefox is far and away the best tool for previewing and testing new sites. The browser's built-in tools are good but the enormous selection of add-ins has brought many powerful tools for people like me. Firefox is so good that many developers preview and test with it first and last. (I don't; ask me why.)
Market Share - Internet Explorer (IE) dominates with about 60% total. Firefox is next with 30%. Apple's Safari browser is at 3% and Google's Chrome browser captured is at about 1-2%. The remaining share includes Opera and the rest of the field.
IE's history has been spotty, which is the reason three versions are still in wide use. The aging IE6, amazingly, commands almost 22%, down only 2 points since the beginning of the year and the arrival of IE8. IE7's share is down nearly 20 points this year and currently stands at 27%. IE8 is rapidly advancing, moving from 1% at the start of the year to almost 12% now. This rapid adoption of IE8 is good news for Microsoft - even though it comes almost entirely at the expense of IE7, those recalcitrant IE6 users have good reason to finally consider upgrading. Firefox has been eroding IE's share but that has slowed since IE8 arrived.
Recommendations - Dump IE6 as soon as possible - it's got security issues and developers like me want it to go away faster than soon. Other than that, any of the browsers listed here are excellent and safe. If you are sticking with IE, move to version 8 soon.