I like Harlot, but seeing as hardly anyone uses it then I'm not particularlly bothered, providing it isn't used in a derogatory sence. Although I can't stand it if someone uses the word Slag (whether it's derogatory or not).
If I'm describing myself to someone then I'll use escort and sometimes prostitute. I have used Harlot, wg, Whore and Slut, but the latter two are used often enough for women who don't work in the business, and causes confusion, and when I've used the first two I find myself having to explain more. Pretty much everyone knows what an escort or prostitute is.