[barrkel]

  Firefox-now: TreeStyleTabs + ok browser
  Chromium-now: fast browser
  Firefox-future: ok browser
  Chromium-future: fast browser

As long as TreeStyleTabs > (fast browser - ok browser), then Firefox is a better choice. Without TreeStyleTabs, Chromium (or Chrome, or whatever fork is better at protecting privacy) is the better choice.

[nandhp]

I believe one of the key reasons for dropping XUL extensions is because they don't work very well with e10s (multiprocess Firefox). I recently had occasion to use a fresh Firefox without any e10s-incompatible extensions installed, and it really felt much faster, so I think Firefox-future may also qualify as "fast browser".