Location, I used to live downtown but now I don't.
But it's also for variety. There are so many other MPs why restrict yourself to downtown.
Combowa is okay but its all asian MPAs which is fine but realize that being ESL their conversation skills are limited.
Toronto Heath Spa is a nice place but a bit pricier than anywhere else that I know of in the GTA.
There's also Bliss (on St Clair forget the cross street might be Bathurst but don't quote me on that).
There's also Plush which is on Dundas West out by Roncesvalle.
But you'd be missing out on SRM (open late), Allure, HFH, Platinum, Pickering Angels and Body and Soul(open late). Check the compilation of compilations section at the top it'll give you give links to the spas and loads of reviews. SRM, Allure and HFH have the best looking ladies on average. B&S has the best price.
Use the advanced search it's your best friend.