I grew both kale and collards this past winter/spring. The kale had too many nooks and crannies for bugs to live while the collard leaves were gloriously healthy, very smooth and much, much cleaner. I'm going to try growing collards over the summer - they are supposed to do fine with enough water. We don't often get hot here.
I grew lots of kale and dried many of the leaves in the dehydrator. Washed the fresh leaves, ran them through a slicing blade (food processor) and then dried them. When dry, crushed the brittle leaves into tiny bits and put them in a jar. Great stuff to sprinkle on so many things, including salads. Easy, convenient, and I don't even notice the taste. I put some in morning oatmeal... No problem.