The vast majority of the 'regulars', here in AB's Technology section, use Firefox. Some others use Chrome or Safari. Hardly anyone uses Internet Explorer.
http://www.mozilla-europe.org/en/firefox/
Firefox is generally regarded as a much better browser than IE but it really excels when you use your choice of add-ons with it. The most popular add-ons are probably the British English dictionary (so that Firefox can automatically spell-check posts like this one) and, as Chuck suggests, AdBlock Plus (which gets rid of the ads on this page, so that it loads much faster).
Chris