We were a party of three adults who stayed in a Riviera studio last month, and have a long history of staying at the Epcot resorts. It is easy to take the Skyliner to the Epcot resorts area if you want to dine there. We enjoyed the dining at Riviera though. Riviera feels more adult and less whimsical than the Epcot resorts, which can be a pro or con, depending on how you feel about theming.
To be honest, the biggest differences to me are the kitchenette and split bathroom as compared to a YC/BC room. Having the ability for two people to have separate shower facilities at the same time made it easier to get ready. For us, a microwave never goes amiss either. Granted, you could stay at BCV and have a kitchenette, but you wouldn’t have the split bath.
Budget is usually my first consideration. I would choose whichever one gave me the best price. I have never had a bad stay at any of them.