...I'm thinking very hard about what it would be if NOT chull. We have some fauna that's yet to be introduced, and some of it might be farmed for meat... but nothing on Roshar is particularly analogous to Terran fauna except for a few exceptions. It's a pretty alien world.
And it's all very well and good to say that it's just... "essence of meat" and not any meat in particular, but I know Brandon is enough of a steak fanatic to appreciate the differences between different cuts of beef, never mind the varieties of chicken and pork. And that's just the staples, humans farm some interesting meats. Still haven't tried snake in anything but jerky form, and that could'a been fake snake. Gator tastes neat. Squid is interesting. I imagine chull tastes like something between beef and lobster, if only because it's basically a bull-sized crab. But I don't think there's any reason for soulcast meat to taste like chull in particular. And if it's based on the Essence of (presumably human) blood, then... Chicken may or may not taste like chicken, depending on whether or not the chicken is a chicken. Fish is presumably fish. So far as I know, the variety is sufficient to cover whatever you'd like to imagine. But it's still fish. There are no appearances of pigs in the books so far, and the word "pig" does not even appear in WoR, but we do have the mention of a "Mabrow Pigherder" in WoK (NOOK, 577). I'm not sure what to say about that, but I'm curious enough that it's going into my box of Brandon questions. I'll ask about it next time I get a chance, but that might be a while, we're in Mistborn stuff right now.