No matter which editor you want to use, you have to learn it and it takes time. A few years back I decided between Emacs and Textmate and learned Emacs - the main reason was because I can still use it when I am forced into a terminal or Windows.
People create new editors cause there is a need to fill.
But isn't writing a text editor one of those garden path problems - a near never ending amount of work to get to just what exists already? I guess I also wonder what inspires developers to start new text editor projects too! Perhaps its just dis-satisfaction with what is there already.
Any debate about them being better really misses the point, it's the dvorak querty argument all over. Better doesn't matter as much as familiar to new users. Textmate is immediately useful to a new user and feels like a modern editor. Emacs and vi look and feel archaic and require too much effort to feel productive in.
That's my two cents anyway after many attempts to use both. Can't stand vi, can get by with emacs just don't really dig it. For quick editing in a shell I just use nano because it's usually just editing of config files.
Comparing how emacs and vi/vim are different from other editors and like saying no one will ever use lisp because of all the parentheses.
The last emacs book was published quite some time ago, and no matter how much of it is still valid, it's just not up to par with providing people with the same level of familiarity and desired features as one of the new ones. At work, we're all using gvim or emacs, but most are aching for eclipse or visual studio.
I try to mention ctags to them and they just stare at me blankly. I suspect the field has started to move rather quickly in the UI and lingual diversity fronts, and it's time editors need to diversify as well.
Still, lisp (or the bastard stepchild, emacs lisp) is a very good language for an editor. It's a shame it's the only place I use it.
I used emacs for 10 years and know lisp quite well but I'm a textmate user now. There are a lot of us.
It's my editing weapon of choice for OSX, Linux and Windows.
By default it's a bit plain, but the plugins available are fantastic: http://taat.pl/en/jedit/
Download it here: http://www.jedit.org/
It has been around for a while, and I think is the closest thing to TextMate under the Gnome environment.