Enemies that spawn are random, so it depends on luck.
Let's say you do today's SP quest.
If you spawn a bunch of Dark Carbuncle, you're gonna get a TON of exp. On 15 ap map they give like 400 or 500 exp each, and around 1k each on 25 ap. If you spawn something like say, Pearl Carbuncle you'll only get like 40 exp.
So on 15 ap
Dark gives around 400 or 500, I forget which
Sapphire gives around 250 I think
and I think everything else might give less than 100 exp