I too have a lot of neck/shoulder issues, mostly after getting a desk job. A couple of things really helped me.
1. Fixing my desk posture. I know, not pillow related, but I paid $20 for a lumbar pillow and never looked back. I also use it for long car trips. Making sure your chair, desk height, and monitors are adjusted correctly makes a big difference.
2. Pillow. I have a tempurpedic memory foam. Medium sized, pretty dense/solid. Buy a water proof cover and it lasts forever; I'm on 9 years now for mine. If you don't cover it, your body oils will ruin the foam.
3. Mattress. Soft or saggy mattresses kill me. We spent ~$1k on a really good quality firm memory foam mattress. It really helps me, and also removed all of my husband's shoulder issues (along with another pillow).
Constantly reassessing posture also helps, but takes getting use to. Good luck!