If your cards fall roughly into these categories,
you can use whattomine.com (fill how many of each you have click the box so they turn either red for nvidia, green for amd) and hit calculate.

With that said, I haven't seen XMR on the radar as a desirable GPU-mining target. I think your best bet right now is EthHash / Equihash (so like eth and related, and zcash and related) things. And of course don't forget about dual mining.