You should work each person's taxes both ways, and see which way comes out better. He may be in a higher bracket than you, so the exemption would be worth more to him. The dependent also would allow him to file as head of household (you apparently could not, since he obviously pays more toward the support of the household), which might save him taxes by having less of his income in higher brackets. He might be able to use the entire child tax credit, while you might not. You may be eligible for Earned Income Credit, so that would help you.
Can't tell without actual numbers on what each of you made. It's not as simple as the one who makes more, or makes less.. Either post numbers, or figure it both ways and see what comes out better.