I love heirloom tomatoes as well, I have had a couple of varieties that the taste is just so goodI haven't been able to go back to the grocery store variety because they taste like nothing to me! I would suggest going to any heirloom seed company online and growing a test garden to see which one works best for you. You can raise them organically and keep the seeds to have your own organic variety if need be but I think you should be able to find both heirloom and organic. I had a crop one summer and got the varieties mixed up and lost the name of the one that was the best I've ever eaten, make sure you don't do that! Please update us on what you find out.
I had to laugh at this response (not at you, just the response..) you see, trying different heirloom tomatoes each year is exactly what I have been doing. With limited space I can only grown 2 to 3 varieties each year, and then I don't always know if a plant is successful or not because of unusual weather conditions. This past year was so bad I have not given any thought to what I learned about the 3 varieties I planted.
I was hoping to take a short cut borrowing on other gardeners findings.
If, however, I am able to find that best tomato, I'll share what I find on here.