Which salt is better Himalayan pink or Hawaiian black?
I think the question is like asking, is kale better than butternut squash? Two vegetables, different tastes, different chemistry -- personal preference prevails. Both of these salts, bottom line, are sodium chloride, but have subtle differences of flavor and trace mineral profiles -- get small amounts of both and try using them where their personalities are evident. If you can have both, I wouldn't worry about 'better.'
I prefer Himalayan at the table and Mediterranean for cooking.
I agree with Susan G's answer. What most people don't often realize is that there are subtle difference in flavors with salts. Yes, indeed they are all sodium chloride but people who grew with Morton's are inclined to think that "salt is salt". I've never been to the Himayalas but if I were there eating yak probably I would go with the local terroir salt. For fish, I prefer sea salt because I like the natural iodine taste over mined salts.
I use Himalyan Pink for finishing a dish, for appearance & texture. For example some type of gread appetizer. The Hawaain black, I most recently used in a potato cheese soup, and tend to use that interchangelably when I need freshly grinded black pepper. I received a huge "salt of the worlds) tasting basket gift last year and its been fun to use. I need to remember to use them all when its appropriate though, since its in my cupboard. To that end, I agree that both salts have different purposes, both delicious but need to be used differently.