As I said,
go to where the money is. The agencies with the biggest inventory of girls also brings in the most money. The most money is because the clients keep booking that huge lot of girls. You will get the best girls from the biggest agencies who house the most girls. It's a no-brainer.
Mirage is near the top. I have used their services before and the girls are better than the average agency. Menus are extensive. You can pick from dozens of girls and Mirage doesn't fool around. They give you alot for the amount you are paying.
There are many famous girls that worked at or came from the Mirage stable of beauties.
I see Heidi is still listed on their website. She has been around for a while and she always gets reviewed well. A girl who has worked for a top agency for a long time and not been replaced is a girl who brings alot to her sessions, is attractive and talented. An agency wouldn't keep her around if these things were not absolutely true. Because if they did and she wasn't great, the agency would lose a fortune in lost bookings (opportunity cost).
Heidi.
Another escort agency is Roommates. But they won't be as good an option for you and it is easy to see the evidence. Look at their schedule. Only 4 girls on during Monday and Tuesday shifts. That is proof they aren't attracting the repeat clients. Because their girls aren't as good as Mirage, they don't get the business Mirage gets and therefore, they don't schedule as many girls during certain periods throughout the week.
http://www.roommates-escorts.com/schedule.php