As I am coming from a Linux world I am quite used to some software that is available for Linux. One of the software I used often was Texmaker. After switching to OS X I used TexShop (as it comes bundled with MacTex) for a couple of years. It is a good LaTex editor and it (besides Latex) also supports Xetex (a TeX typesetting engine that uses Unicode and system fonts) out of the box and it nicely updates PDF documents almost on the fly.
But I recently switched back to Texmaker because of some of its strengths that I really like (most UI related):
- one window
- auto completition of commands, references ...
- a lot of icons for math symbols
- document structure on the left side
- quick access to almost every LaTeX command from menus and most often used ones from drop down menus
- a better search box (although I would like it to be incremental like in Emacs :))