I've heard a lot of hunters say, "If you like deer liver, you'll
love elk liver." And that's certainly not true. Mule deer liver has been a favorite in my family as far back as I can remember, but how we feel about elk liver varies from "tolerable" to flat out "don't like." For me personally, elk liver is "tolerable."
I've never tried moose or antelope liver. They might be okay, but not even all of the mule deer we've killed had good livers. I'd guess about 90% of them did, but not
all of them did. Many, many years ago my mom taught me how to tell whether or not a deer liver is worth carrying back to camp - you just push your thumb and index finger inside the liver, and pinch a piece of it. If it feels "grainy," just leave it behind with the rest of the gut pile.
I've also heard hunters say they've actually seen liver flukes in deer and elk livers. They said liver flukes look like little, white ray fish swimming around in the blood. I've never seen them myself.
I tried deer heart once. It was okay, but to me, it wasn't worth the effort of carrying it back to camp. Besides, deer rifle bullets often make messes of deer hearts.