I agree with Destiny11.
Both will likely lead to interviews, but, in your scenario, I would be persuaded to think that the individual with a more average GPA, good DAT, and many ECs has an edge.
If the situation was:
2.9 GPA, 17 DAT, several excellent ECs
VS.
4.0 GPA, 24 DAT, no ECs
I would think that the person with higher grades would have an edge.
But then again, I'm no adcom 😛