Sure, you can get Microsoft Word, the ultimate text program, which can drive you to the store, buy breakfast, cook it for you, eat it for you, then drop you off back home.
And when you are writing a book or other elaborate project, there’s nothing like it.
But for everyday notes and pounding out fictions and essays, the handy little shareware Tex-Edit Plus fits the bill perfectly.
It is lightweight, very fast, and awesomely stable. Back when Apple’s built-in SimpleText/TextEdit was too simple and cranky, Tex-Edit came along to carry the load, and those who started using it then have never stopped.
It’s fine for the most basic use: pop it open, type, save. Then do some basic formatting, change fonts, save as RTF or ASCII or Word, and leave it running quietly in the background, ever ready.
If you feel adventurous, do some exploring, because it has lots of capabilities— record sound, choose from a variety of Applescripts, write html code, and clean up or sort text.
It is also the most polite of sharewares— does not nag, expire, or turn purple (unless you want it to.) This surely has cost developer Tom Bender some revenues over the years, but has also made him legendary. Tex-Edit Plus is like a good pencil— it does exactly what you want, yet supports finesse. And, bonus, it never needs sharpening.