With sways, you got endlinks, too. Endlinks have bushings, so I'd buy them new. Sways can be bought used, since a little paint scuffing doesn't matter (if it bothers you, rattle can paint is cheap).
Solid sways are stiffer than hollow sways. I'm a fan of Whiteline. Size is dependent on spring rate. I like the 24 F / 22 R combo, because you can bump them up to 26 / 24 if you choose to upgrade springs, and not have to buy new bars.
Endlinks, I like Kartboy.