Major reason to use TextMate is that it's got a good file tree overview, like eclipse. I find that working with rails and constantly looking around and inspecting the file tree is very pleasant in textmate. I like emacs, but not for jumping around between files, and the speedbar is horrible. On textmate if something happens in the file system it's instantly reflected when you switch back into textmate. I wish the speedbar would recieve a good rewrite in emacs.

Otoh, development on textmate seems to be pretty slow or nonexistent, it would be nice if split view would have been implemented by now.