Let's see my choices.
Mummy- Okay, that is definitely pretty bad. Decaying corpses and human jerky. Bleh.
Virus- Well it's so tiny, it probably won't have any taste. Would certainly make you sick though.
Otyugh- I...really have no idea how these guys taste. But going by what higs said, they're probably not good.
Parasite- Oh come on, it's just a bug thing.
Scorpion- Meh. Besides being poisonous, nothing.
Devourer- Eh, worms and stuff aren't my preferred meal, but it can't be that bad.
Flying Arsenic- This is asking for worst tasting, not most dangerous, so eating a flying poisonous dagger would just taste metallic and poisonous.
Lava golem- hot rocks. Wait for it to cool and wash it down with water
Flesh spider- Just a spider. No big deal.
Crimson Dragon- Hey. I'm actually curious to how these taste.
Elite Immortal- Does it cross into the realm of cannibalism since immortals are sort of human like?
Shard of focus- Crystaly. Meh.
Scarab- Just another bug
Graboid- Honestly, no idea, but I'll just assume it's a big worm like thing.
Chimera- Who knows what the heck went into that. Still probably not very bad tasting.
Vulture- These probably actually taste good.
Lycanthrope- Er....that thing looks emaciated. And also human like.
Malignant cell- Same as virus.
Armagio- What...is that? Some giant robot thingy?
So based off all of that, I'd probably say the worst tasting would be mummy.