Based on my own experience, I think Chrome hits the nail on the head because usually the only helpful thing in terms of finding the right tab is (1) the favicon and (2) the general position of the tab among the other tabs.

General position is particularly helpful because, from left to right, it roughly represents "time opened", earliest to latest.

Firefox doesn't help me find the right tab just by including an 8 character width along with the favicon. Might as well just get rid of those 8 characters.