I'm not even sure Sprint has an equivalent to the DX. The phones are very different. Sprint has a lot of HTC phones - mainly comparable to the TB.

I hate to say it, but if you want a good reliable reception, you'll have to go with an old feature phone. None of the smartphones I've ever had have ever  had as good reception as my older phones (EnV3, EnV2, EnV, LG flip phones, etc)

My Droid X has good reception, I've never had problems not being able to connect to a call or dropping any calls or anything. The only reception problems I have are with 3G and my internet not working. My texts don't go through as much as they did on older phones as well.