As for the difference between StarKist and others, I've never in my life tried to figure that out. And I should. What would you, or anyone, say the differences are between the major brands?
The only "distinction" I've made in recent years is getting pouches instead of cans. That started when I was trying some real low-carbing just for the heck of it (it worked), and I learned from others that it's easy and convenient to take pouches with you to work or wherever and eat it right out of the pouch, or dump it out and throw some S&P on it, or whatever. And it's dry in comparison, which we found appealing.