I was originally gonna titled this "least favorite", but least favorite would imply it has been favorite at some point.
Anyway, the title basically says it all. What's your most hated monster to fight?
By that I mean which monster would you refuse to fight because you hate fighting the monster that much?
As for me, I'm gonna have to go with giant rats, cows and hellhounds.
I do like fighting all sorts of monsters, including weak ones like Al-kharid warriors and barbarians in Barabian Village.
But those monsters I mentioned give me NOTHING, nothing at all.
I could make something out of what the cow drop and cook the meat. But is it really worth fighting for that? No it isn't.
Also, I will admit that the hard clue scrolls from hellhounds are worth it, but I want to be able to get something useful while hunting for these clues, which I can easily do with greater demons, red dragons, steel dragons and nechyreals, so not worth fighting hellhounds for them.
So yeah, you got the point of this thread, now answer the question.