I left Internet Explorer for Firefox because I was unsatisfied and jumped to the first viable alternative. I left Firefox for Chrome for the same reason. I'll jump to the next viable alternative as soon as it's available.
What irks me about Firefox is that tabs aren't separate processes, so one sticky tab will make everything sluggish, but that's about it.
[1] https://www.mozilla.org/en-US/firefox/sync/
[2] https://docs.services.mozilla.com/howtos/run-sync-1.5.html