That makes sense, just serprised at the quality you recieved. Ofcourse I have had to get my HO from other places besides them but the quality was still good for the most part. Too bad I dont have room or money to order the amount of hides I would have to get from them to cover my different uses.
Back to the OP's question it would depend on style of belt you are making and personal preference, durability, and everything else. If your going to be tooling the belts then vegtan. Personally I would go with a back or depending on if you have other projects you can use the side for get sides and use the top portion for belts then the lower portion for your other projects. Double coolattas or whatever they are called are nice as well.
If you are not tooling and want a nice durable belt that you dont have to dye then look at things like english bridel,latigo, harness leather. Again you would have to get some samples to see if it is where you want to go. Most tanneries will give ya some swaths to show you the leather.