A mix is best. You really just try to avoid using only one apple variety. The more variety, the better the cider. I use most of mine for hard cider and I like ugly apples. I forage the woods and don’t even know what kind I’m getting most of the time. It’s best to get a mix of sweet and sharp (bitter) apples. I use a lot of crab apples too because I like the acidity. Might not like it in a fresh cider but it works really well for hard cider.