Firefox all the way!
Mostly because of the deeper integration possibilities of the plugins. I was on Chrome for a while because of some really annoying Firefox bug a while ago, but I couldn't stay. And IMHO there is no worth mentioning speed different between them.
A few times a week I use Edge for some Mediastuff which doesn't run to good in Firefox on my HTPC and I have to admit: Edge is super fast. It's start and rendering feels simply super fast against all other Browsers.