As a matter of fact, AMD is really shit compared to NVIDIA when it comes to equihash. Just there aren't any public miners that really utilize NVIDIA cards the proper way. I played around a bit and I got almost 50 Sols/s on GTX 970. I also heard from some other devs that pascals are even much more efficient. Trying to get a some pascal card to test this in practice.
Yeah, some devs claimed that NV pascal cards can do at least 130-160 Sols/s, and sad no devs release any advanced zcash miner for NV cards yet, but im sure it will come later just like it always does 