In my experience, Asian providers have proven more disappointing, for lack of a better word.
First, it's harder to determine what you're going to get because more fake photos in ads.
Second, when you do take the plunge, it's almost never the impossibly hot girl you saw & drooled over as she strolled by you in metrotown.
Finally, when you've done your homework and think you've really found "that girl", you're often paying a huge premium, and she's likely super busy because there's a million guys like you who have been looking for her also and trying to book.
Again, that has just been my experience.
White, Latina and other girls, I've managed to find a fair number who are pretty much fantastic, enough so that I get plenty of variety without compromising quality.
Not only that, but I even find a number of bargains, relative to the $350+ price point you pay for a lot of the "higher end girls". Truthfully I can't think of any reason to pay that much, based on my experience, other than if you're looking for something very specific and you find a girl who meets that criteria and she happens to be in that price range.
TL;DR
I've found I can get much better bang for my buck in terms of balance of price, service & appearance with other girls besides Asian.
To be perfectly clear for a third time, this is just my experience from 5 years in this hobby in the lower mainland; I hope it helps.