The Firefox tab bar is naturally more usable than the Chrome tab bar with large numbers of tabs because it scrolls rather than trying to fit them all in the bar. (I sometimes wonder whether squeezing tabs to the point of absurdity was actually a conscious decision by the Chrome developers to limit the number of tabs people can open and thus memory use.) There are a lot of Firefox extensions that add additional tools to manage large numbers of tabs, of which Tree Style Tabs is perhaps the most popular. There are not as many Chrome extensions, since Chrome's UI is not as extensible.