Although I don't use them exclusively, I voted humans/humanoids with class levels.
I like to use primarily humans/humanoids with class levels for several reasons. They are the most interesting and difficult opponents. Also it's very difficult for the PCs to know what their power level is. The beggar who accosts them on the street couuld be a Com1 or a Monk15. Also I like city adventures and they're mostly human/humanoids of course.
Other than that I like undead (with class levels), dragons and outsiders.
I like to use primarily humans/humanoids with class levels for several reasons. They are the most interesting and difficult opponents. Also it's very difficult for the PCs to know what their power level is. The beggar who accosts them on the street couuld be a Com1 or a Monk15. Also I like city adventures and they're mostly human/humanoids of course.
Other than that I like undead (with class levels), dragons and outsiders.