If you need to crack NDA examination then you need to have a good foundational knowledge of mathematics. So to build concepts both the books are famous. Personally, I feel RD sharma is more elaborative about its theory than RS Aggarwal.  But RS AGGARWAL has some really good problems. So if you can use the both as you will get a diversity of problems.

I hope my answer helps. All the very best for your future endeavors!