Used Firefox for years, switched to Chrome for most of 2012 when flash was causing so many issues, with a few versions of Firefox, and I was crashing frequently enough for it to be a nuisance. Switched back to Firefox earlier this year, I think it was 21.0 that finally had things running normal again. Chrome was a bit of a resource hog and the differences in my uses were so negligible when I reused Firefox that I switched back. Always preferred it's handling of add-ons, user scripts and theming.