I like wysiwyg but I like FCKEditor better.
This is the editor I use for all my programs. It supports many languages and it works pretty neatly. Though it takes some time to load on the page, if you don't want to use it on every page and just on some small pages... That's the editor to go with.
My opinion only. This is no fact and just my advice to you. Maybe there are better editors out there that I don't know of so keep that in mind too.