Hi Ken,
I don't have huge experience with heirlooms, but I see we're in the same zone, so I'll let you know what's worked for me here.
Favorite cherry: Black Cherry. I like the flavor, I think it's a lot more complex than any red or yellow cherry I've had, and it was by far the most vigorous tomato plant in my garden - vines at least 15 feet long and covered with fruit. It was my first and last plant to produce fruit this year.
Least favorite cherry: Yellow Pear. I try these every year because my husband likes the flavor, but the plants just don't fare well. I end up getting only a handful of fruit off of each plant before it dies in mid-summer. I'm not sure if it's the heat, humidity, sandy soil, or what that affects it so badly, but it doesn't seem to be afflicted by a particular disease.
Favorite for processing: Roman Candle. Not a lot of flavor for eating fresh, but make a good sauce or salsa, very little juice or seeds, and a thin skin that I could leave on in sauce. Also, the plants were incredibly prolific for me, and although the fruits weren't as big as I expected, there were enough of them to make up for it.
Least favorite for processing: Pink Oxheart. Maybe I haven't given it enough of a chance to list it as a least favorite, but I was very disappointed in this variety. I started 20 seeds and only had 4 germinate, all of which died before producing any fruit. They just seemed to lack vigor in this climate.
I haven't grown many beefsteak-type heirlooms, so I can't choose a favorite in that category. I did have two standouts this year for fresh eating, though, each with its own strengths. Mountain Gold was great in salads, with a firm texture that stood up to slicing and a rich, savory taste. The plants did not produce a lot of fruit, and the fruit weren't huge, but I'll grow them again because I loved the flavor. Striped Roman was a big surprise - they were meant to be for processing, but they were so tasty and beautiful that I ate a lot of them fresh instead. Ripened very soft and juicy - the kind of tomato you need to eat over a bowl to keep from staining your shirt. The flavor was exactly what I expect a summer tomato to be, with just the right balance of sweet and acidic. They were much bigger (though less prolific) than the Roman Candle.
