There are so many slight variations and nuances that change harvest to harvest, slightly different grades of teas have slightly different qualities, so that it's hard to tell you exactly which tea to buy. I've had good enough experience with this shop to trust that what they send is going to be very good--and not just the most expensive grades either.
If you can swing it, I'd suggest picking 3 or 4 of the Anxi oolongs--one pricier TGY, the inexpensive Huang Jin Gui (I got a quite delightful HJG inexpensively from Norbu recently, and it was very popular around the office), and one or two priced in between. And then try the same with the Wuyi Yanchas--one expensive/fancy grade, a cheaper one, and a couple in between.
If you brew them in smaller batches--2-4 oz of tea per infusion--you can get quite a few sessions out of a 25 gram sample package, and get a good feeling for which of the teas you might like to buy in larger quantity