Oh yeah, grells. Chokers, dragonnes, kobolds, sphinxes and savant hydraes were my first love, but as I read more stuff on D&D's unique monsters, beholders, illithids, grells, and other aberrations. I liked the new Fiend Folio a lot, because it had kaorti and ethergaunts, both of which are very nifty.
In fact, the only monster category I don't especially like is undead. Then comes vermins, plants, animals, etc. They're useful and needed, but not especially interesting. All nutrient, no flavor, if you catch my drift. You can't not use them, but you need extra spice otherwise it'll be bland.
My favorite D&D spices are aberrations and magical beasts, followed by dragons and outsiders.