Overall impressions of each as of this point:
Cherokee Green- Excellent flavor. Good production. Weighing in between 6 and 12.2 oz., little if any cracking, held flavor despite all the heavy rain this season. This will be back in the garden next year. In fact, I plan on planting two and trying Cherokee Purple as well.
Black Krim- Production is high. Flavor...can't say. I have yet to get one that didn't severely catface or crack before starting to blush. I do think that this would be a great tomato in a drier season. Fruits have weighed between 3 and 13 oz. Most likely will not be back next season due to susceptibility to catfacing and cracking.
Opalka- Production is good. I think I would have had more tomatoes if I amended my soil better before planting this season though. Overall it is a healthy plant. This is a great tomato to use for salsa. Easy to dice without turning to mush. It has very little juice and lots of meat that tastes very good. This will make a great sauce tomato as well. These will definitely be back again next season.