The new Firefox Quantum is incredible. I've always been in search of the best browser continually for years and always had things about each I didn't like. I've used Chrome as my default since 2008 and though I use/used FF, Opera, Vivaldi, Yandex, Maxthon, and others none could ever get me to switch from Chrome. The new Firefox Quantum got me to switch.
The comparison for me is like playing CSGO at 40fps and then playing it @ 144+fps on a 144hz monitor. Chrome and other browsers constantly drop frames and stutter and lag. I've yet to see Firefox Quantum lag or stutter at all.