I have both and wouldn't buy either. The Radeon VII are good card when they don't burn up. I had 8 Radon VIIs and I had to RMA 5, when I put the 5 back to mining one burned up so I sold the rest. Its a common problem lots of failures. The RX 5700 are great for eth only, they have very fewer miners work with them and they are only efficient at mining eth.
damn that's a lot of RMA, any idea if it could be your case or mother board. I had a shit Chinese mobo and a server case that kept killing cards over and over.
I had them on two different rigs, if you read the Readon VII thread lots of miners have had failures. Its a shame, very efficient and can mine other algos like griin 31 with decent results.
https://bitcointalk.org/index.php?topic=5107271.380