I mostly use big, dumb, slightly-piggish green orcs, but occasionally I'll throw in a more Warcraft-like tribe. I have an adventure in the works where the PCs will deal with a subtly evil human tribe (or at least the leader's evil) and a good orc tribe.
I like to make the goblins the clever type, but chaotic neutral. They're cowardly when alone, but get a group of them together, and they'll set traps, set up ambushes, and try to surround and mug you, but if you give them some food, they'll probably go away.

I always think of this one scene from a game where there's a royal wedding and the goblins storm it. The king simply invites them in and offers them cake. They accept, and at some point leave chanting, "The king is great! He gave us chocolate cake!"
Kobolds are kind of like goblins with inferiority complexes, and more likely to be evil. And they're always the lizard type, though I've thought about including both lizard and dog kobolds as offshoots of a single race but who now hate each other (like the Githyanki/Githzerai, only on the PMP and with a lower CR).