I think Tryst is the most reliable. Models-world? Eh. I don't know of any woman who uses it. When I google a provider I'll see a models-world ad sometimes but they're almost all very old.

 
But as usual, without any other "verification" it's a crap-shoot.

To be honest, I don’t think any lady ever advertises on that site. It appears to be a site that simply scrapes the ads from other sites and hopes for some random search to return on a providers number. Not exactly sure how they are making any money.

Thanks for all the feedback, I see models world pop up mostly if I Google an email address. I'll definitely not take them seriously. Good to know that tryst is fairly reliable