I think Black Krim was the tomato I tried at least twice that always cracked and split for me and then rotted so that I could never get a ripe fruit. Cherokee Purple I did grow last year. It was a nice tasting tomato, not overly productive but not bad for an heirloom. But I seriously doubt I will be growing it again. I have tried Brandywine, I was lucky to get one tomato off a plant. I can't see what the fuss was all about on the supposed flavor. Yes, it was good but geez. I have tried other heirlooms also and I should be sticking to my hybrids.
Karen, you want a sweet cherry tomato try Sungold. It is yellow and sweet and tasty. On the cherry and grape tomatoes I am growing Sungold, Sugery, Sweet Million and Juliet.
I have some, actually quite a lot of tomato seeds but never have started my own. Always just buy plants.