The types of kale tasted were: Lacinato, Red Russian, Blue Scotch Curled, Red Winter, Siberian Dwarf Improved, and Dwarf Blue Curled Vates. In the tightly controlled testing, several VegHeadz plucked a piece of a leaf from each type of kale, ate it, and then we compared notes. The unanimous winners were the Dwarf Siberian and the Dwarf Blue Curled Vates, the very best of all. The individual criteria for "best" seemed to be tenderness and "sweetness" as in lack of bitterness.
The main thing we learned is that each variety tasted slightly different, and since all but the Lacinato were grown in the same bed under the same conditions, we assumed it was differences in variety, although different growing conditions can produce taste differences also.
It was fun, and you should try your own taste test. It's a good idea to plant several different varieties of any vegetable as each variety not only tastes different, but is more or less susceptable to pests and diseases, and more or less tolerant of various growing conditions. Planting different varieties increases the chances you will have at least one variety that does well.