I think the biggest key to a good tuna salad it to make sure that you mash and mix the tuna until it is in very fine pieces. I typically get light chunk tuna in water and mash the hell out of it before I start adding anything to it. Unless you buy high end canned tuna in olive oil, it is going to be dry. Leaving it in big chunks only emphasizes the dryness. I think high end canned tuna or fresh tuna would be wasted in a tuna salad.
Using canned mackerel instead of tuna makes a good tuna salad alternative. If you’re tired of the mayo based salad, try mixing tuna, salmon, or mackerel into hummus instead. Tzatziki is another way to go instead of the usual mayo. If you’re making a big batch of tuna salad, try mixing in a little bit of canned sardines, kippered herring, or smoked trout into your regular tuna salad for a more varied taste. I’ve been trying to increase my tinned fish intake beyond just tuna. Sardines, herring, and mackerel are typically better for you to eat on a regular basis because they have lower levels of mercury. Used to love sardines as a kid but stopped eating them for some reason or another. It’s taking me a while to get used to them again as they do have a much stronger flavor than canned tuna.