Are you looking for something free/open source?
Do you want absolute WYSIWIG or simply a good text editor?
Are you familiar with HTML tags?
If you want something that will also assist you in your overall site management and are willing to pay money, then you might consider Adobe Contribute. For a small site maintenance, this is an excellent tool. I have used for some of my small site customers. It allows them to be pretty much in control of all of the content and content updates. It's $99.00
If you are comfortable with HTML tags for formatting, then a very good editor would be HTML-Tools. Full support for that is current suggested price for it is around $59.99. If you want to try it you can do a free download with 30 days use. I personally like this and have used it for quite some time. There is a free older version called HTML-Kit v292 which works just fine; but is a bit less polished the the newer Tools. The site is at: http://www.htmlkit.com/
If you are looking for free; then CKEditor might work just fine for you. I've not used it so I can't speak for what's behind the curtain.