I generally like the monsters that are basically the combination of two animals, or even a man and an animal. Stuff like owlbears and beastmen have a strong connection with ancient myths, as well as more modern tales like "The Island of Dr. Moreau". Many gamers make fun of them, as they appear ridiculous or are biologically impossible. But D&D and S&W are games with magic, so I'm perfectly comfortable with these types of monsters.
You can set up an adventure locale with these creatures as roaming animals just looking for food. They could also be something horrible like the broo from Glorantha, who reproduce by raping women and who use people as a food source. And then there is the mad wizard who is trying to create a new form of life. These possibilities cover the natural cycle, a source of truly intelligent evil, and possibly a morality play, depending on how you present these creatures in an adventure.
I'd like to see a wilderness map, maybe just a single hex (as Judges Guild used to do), that covered all three possibilities. There could be an old tower, where a mad wizard is warping the local wildlife, and then releasing them after not being satisfied with the results. Some of these creatures just wander off and basically survive in the woods like normal animals do. But some of them are intelligent, and go to a wilder area away from the eyes of their creator. Here they might find a small village and plunder it, using the population for food and breeding stock. Eventually, they start slave raids into neighboring areas. This brings in a band of adventurers, who naturally think the mage is behind the attacks. And things move on from there.
I know there was a Ravenloft kingdom that had a Moreau aesthetic. I'm sure there was at least one older D&D product that featured such an area as well (I believe it was in Dungeon magazine). When done well, these creatures can really be a good challenge for players. Even those who think these monsters are goofy.