For a couple of days I have been evaluating where I will go and where I will recommend others to go once Firefox migrates to becoming a watered down version of Chrome (and Cyberfox' last release becomes outdated).
Main contenders have been:
路 Iridium
路 Brave
路 SRWare Iron
路 Waterfox
路 Pale Moon
路 Comodo Dragon/IceDragon
I will go with Pale Moon (http://www.palemoon.org/).
Seems to me it is more customizable, long term viable, open, etc... (or just less broken by design) than the alternatives.