Zestar has a decent sweet-tart balance. If I were to compare its acidity level to something you’ve likely had, I would say it’s close to that of a McIntosh. It should ripen around early August in your area. They are just starting to ripen here and are still a little more acidic than I remember, but I didn’t pick them last year until the yellow jackets started to notice them.
Early apples aren’t really known for being low acid (if that is what you are looking for), and people generally don’t give a good explanation on acidity levels, so it’s hard for me to be sure, but in my notes, I have Beacon as “mildly subacidic” or “slightly tart”. Maybe someone who has tried it can give their opinion on it.
Beacon should ripen a week or two before Zestar, but it lacks in disease resistance. I suppose it ultimately comes down to what type of chemicals you are willing to use and how often you are willing to use them, but the category of apples you appear to be looking for is already very limited.
