I know a secret

And it's a surprise: the best juice comes from crab apples.

Admittedly they were ripe red John Downie, but straight off the tree they were still a lot more like hard red berries than proper apples, and they were the devil to crush. I got three pints from a gallon of mush, and it was sweet and appley with a lot of the puckering richness which I think is malic acid. Drinkable - delicious - running off the press.