If you had to choose only one
 

John Berenyi wrote:
I have two rigs. An NRD-515 with matching speaker, memory unit, and extra
filters with the Gilfer 10 turn pot. The other is a Drake R7A with the RV75
and all the nice filters with aux 7 board plus ms-4 speaker. I can only
keep one. Which would you keep?

Those are some of the finest receivers ever made. I have both.
Marvelous radios!

For sheer DX performance, keep the R7A.

For reliability and longevity, keep the 515, it's built better. My R7A
has had components fail, whereas the 515 just keeps on truckin.