that's a tough one, because yeah if you don't have a good brain people will try and take advantage of you, but if you don't have a good heart you'll be the one taking advantage of others. I'd have to say a good heart because I've noticed that doing more kind things for others bring more happiness then just knowing stuff.
I agree with EatLovePray that people will exploit you if you have a good heart but no sense. I think though that all things being equal, most would agree that having a good heart is better than being intelligent. It's unfortunate that in our modern society, having a good heart comes with unfortunate consequences.
Talking physically...I think both are inter-related. A healthy heart can function only if the brain is functioning and vice verse. It all ends up with our good physical health.
If talking about your personality whether being brainy is good or being good at heart...then I would chose to have a good heart 'cause I understand people would make a fool of my good heart by tricking me into stuff but eventually it's the KARMA points that I will accumulate and that matters the most in the end!!!