Although I typically work in OSX I do often use Windows and Linux platforms. Right now I will focus on the Unix based editors. I will focus on 3 and will try to convince you on why I think the one I use is best.
emacs – This is one editor that I HATE. I know some people who will swear by it. They will say that once you get used to it, it is very handy. I’m not saying that this isn’t true, but for me it definitely wasn’t. It just makes everything hard by straying away from what your used to. Simple tasks like copying and pasting are harder than they need to be. I would not recommend emacs.
TextEdit: This is the default editor that comes with OSX. It does everything you need and behaves as you would expect. If you don’t want to download anything new and just want a simple text editor TextEdit will be fine for you.
Kate – Kate in my opinion is the best text editor. It does everything that you want. It color coordinates things so coding in C++ is made easier. There is a built in terminal which makes running code a breeze. On the side you can see all the files that you are working with as well. Thanks to great organization and functionality Kate is one of the best text editors.
simplyze 