I use SRware Iron, which is a Chromium-based browser compatible with Google Chrome extensions, and my favorites are Cache Killer, Flashblock and Bookmark Button Startpage as the default extension to improve my browsing experience. I have like another dozen of favorite extension but aimed to perform specific tasks, hence these are not always enabled because the more extension that one enables, the poor surfing experience.
I use Firefox and my favorite extensions are Adblock plus, Hola, Greasemonkey, Downthemall and Firebug.
AdBlock Plus, because, well.. I don't like ads. NotScripts/NoScripts is also pretty good if you don't want additional clutter on your pages (even though some may disagree.. Other than that, I just use a twitch.tv workaround that makes stream run smoother for people from Europe.
Definitely adblock.. ads are so intrusive and if anything, will make me hate the brand even more than I already do lol. If we are ever forced to endure it, I'll be turning my computer off for good.
I don't really have that much browser extensions because personally, i think they just slow down the browser. However i really find the Adblock Plus really useful. It's pretty much the only browser extension i have. It really does the job of turning off those annoying pop.ups. I find those other browser extensions to be unnecessary to be honest.
I think the most handy ones are AdBlock free so that my webpages aren't full of ads and popups that sometimes can be quite embarrassing. There is also Youku Unblocker which allows me to view videos that are not available in countries other than China.
I blog for fun occasionally and I find Deepest Sender to be a great extension. It's a Firefox extension which makes it easy to post your articles on Wordpress, blogger and a few other blogging platforms. Since I also hate ads, my other favorite extension is Noscript. It kills all ads and 'murders' all scripts except those I permit to run. With such scripts disabled pages load very fast.
My two absolute essentials, and the ones I always need to have installed are AdBlock Plus and HoverZoom. Adblock is a must of course, it gets rid of all the ads you see online, I even forget that ads exist, as for HoverZoom it's just a matter of convenience, it makes it so that every picture online can be previewed just by hovering the mouse over it or over the link.
I use the ad block extension which is quite helpful in Firefox. I think it is quite important to certain extension to make your browser completely great. Browsers can become really plain without the use of extension. I have a lot of things to try out in extensions and hopefully I will be able to do that very soon.
