ICECAT JUST GOT UPDATED!!!!
posting copypasta to help newbies:
The best firefox fork with freedom and privacy as its philosophy is GNU Icecat, which actively removes bad "features".
Icecat is portable, and can be contained in a single folder. It's severely fanatically pro-freedom and privacy. It's more secure than vanilla firefox with just as much room for hardening. It's stable, and the only frequent updates it gets are security updates.
you can get it at http://www.gnu.org/ or just go straight to https://www.gnu.org/software/gnuzilla/ and select https://ftp.gnu.org/gnu/gnuzilla/ and choose your version from there.
remember, if it's too slow, you may need to reenable hardware acceleration in about:config and don't forget to check about:permissions as well
when you have your browser "tar" file you can right click and "extract here" then search through the files and make changes as you please. inside "browser" there is the folder "searchplugins" delete those, they are undesirable and you should choose your own later.
There is also the "blocklist.xml" file, which if you have custom settings for can be a huge help.
GREAT NEWS! UPDATE!
gnu icecat USED to be mysteriously slow. With hardware acceleration enabled it functioned a noticable amount better, and with these addons (listed in addon info) and about:config and about:permissions edits, is significantly improved, yet still slow at rare moments.
but now:
https://ftp.gnu.org/gnu/gnuzilla/
https://ftp.gnu.org/gnu/gnuzilla/38.3.0/
newest icecat version 38.3 is out and is LIGHTNING FAST NOW!
for the adblocker
http://pgl.yoyo.org/adservers/
https://easylist.adblockplus.org/en/
https://adblockplus.org/en/subscriptions
You should also follow my paranoid guide to harden the browser and make it more easy to use and efficient.
http://8ch.net/cyber/res/35041.html