I like to eat the Black Widow first, because there are usually some new players down there, which are extremely easy to kill.
Another reason is because other than these new players, evolved and pro players rarely go down the pit, so the chances of you running into something that can kill you as a Demonic Imp while down there are pretty small (But it's best if you scout the area first, just in case).
While I do like killing the Yeti, most of the times I go there someone already killed him, or a Reaper is camping on the Ice Biome.
Mummy is decent, but it's far from the grasslands so you have to travel a long way just to kill him.