Yes, it seems like another post about the best editor for the Mac. I spent two months using Textmate as my main editor for various stuff, but mainly tex and R editing. I always used Emacs before, but I decided to give Textmate a try, juste once again. Note that I am using the MacOSized version of Emacs, namely Aquamacs.

Hereafter, I enumerate useful functionalities that are expected when using a text editor for coding or text editing (I emphasized the conjunction because my own texts mostly are in text or tex mode). For keybinding, I use the convention from Emacs and Textmate communities, where M means the meta or escape () key, C the control () key and A the alt () key.

Action Emacs Textmate
switching buffer/window C-x b ⌘`/⌘~
filling mode M-Q
auto-fill-mode or fill-region
forward/backward search C-s and C-r ⌃-s and ⌃⇧s
rectangular selection (1) C-x r r, (2) C-x r k, (3) C-x r y
kill-rectangle, copy-rectangle-to-register, yank-rectangle
press while selecting with the mouse
code folding M-1 C-x $
assign to selective-display the value 1
F1 or click the opening or closing arrow in the gutter