There has been discussion over time about the purchasing of roasted beans and from where here but nothing specific about what is best.
However, if you look up in the cupping room, where people have posted their comments about various green varieties which they have roasted themselves, you might get some ideas as to what to try. Most of the members here are really good at describing their roasts.
Most commercial roasters like Veneziano and Cosmorex Coffee will do Single Origins as well as blends. Youd have to have a good look at their websites to see what they are roasting or even better give them a ring.
Ultimately its kind of like wine tasting, you need to get out there and try different varieties and roasts to determine what your palate likes and dislikes. Of course visiting reputable roasters who are passionate about their coffee will, like a good vineyard, show you their best product and help you on the path of finding what is great to drink!
But, Id be having a good read of the cupping room, Adam.