Nah. There tottally is a vanilla tier of monster fucking.

Vanilla tier is monsters that mostly look human asides from some minor in-human traits. Vampires are good example of vanilla monster fucking. So, are cat girls.

And to give an idea what the other tiers are like:

Next tier would include Anthros (Furries), Lamia, Centaur, Mermaids and other similar monsters.

Then the next tier would include Human-faced beasts (humanoid head and monstrous body).

Then the final tier is literally fucking actual animals like dragons. Don’t do this. Only villains do this.