Not had puffin per se, but a friend had a couple packages
of seal and a couple of auk that he'd gotten from a relative
who is authorized to hunt such things; he cooked some
seal and found it okay and cooked some auk and found
it utterly disgusting, so he threw away the other package
of auk. When I came to visit, he proudly defrosted the
other package of seal and discovered that he'd kept the
wrong package. When he described the taste of auk, I
suggested a line of attack. We brined the birds, removed
all the skin and visible fat, parboiled them, soaked them
in a soy-ginger-garlic marinade, and grilled them. They
came out tasting sort of between marine duck and
land-based duck: i.e., okay, not much better than that.

I'd try all the other foods listed here except possible the
whale come and the casa marzu.