Firefox. I can accept people using Chrome, it's very quick on it's toes. Safari... maybe, a hint of laziness there. IE, get the hell out and never come back.
I don't like Firefox's plugins now currently I'm using Safari found it's very quick and neat. Don't know why friends disregarding it. Now I am looking for the browsers performed best for webgames.
Firefox is my main browser but I'm also partial to Pixelfari. I tried Chrome but deleted it fairly quickly, it's a fast browser but if I need speed over plug-ins Safari works in a pinch.
They generally disregard it because plugin-wise it's like the Android Store where Firefox is the App Store. Plus it lacks a bunch of features and makes some incredibly stupid decisions I got frustrated with within minutes of using it...
I use Chrome for its speed and simplicity. Hate IE's sluggishness, cluttered display and the fact it takes 10 times longer to open than Chrome!
I'm using Palemoon -- a version of Firefox 4 which has been optimized for Windows. It runs noticeably faster than the vanilla release. http://www.palemoon.org/
I also use palemoon I couldn't live without the plugins and I don't even want to try chrome as google knows to much about me already and I don't really trust a companys whose sole purpose is to target ads at me. I don't want safari because if it's anything like itunes it's completely useless and as for opera I've just never liked the GUI, although I'd use all of the above before internet explorer. On linux my favourite browser is epiphany which I guess is sort of like a stripped down firefox but seems much faster if it was on windows I'd use it there too.
Opera, with a mix of Chrome and Firefox. IE9 is no longer cluttered though. Giving it another chance.
Chrome as much as possible. But I have to use my sister's 6? maybe older? year old mac a lot and that can't even run chrome. So I use firefox on here.