Downloaded VeriFLY for March 2022 cruise. No problems with it and I liked the idea of ‘one stop shopping’ to show docs when checking in. That said, we didn’t use it because there was no one in line ahead of us to speak of and we had everything we needed in Apple Wallet/Health/photos. Other friends used the VeriFly liked it and the speed process at check-in.
As for Medallion App we’ve used it before and love it.