Trigger on the AR is better,
Integral scope rail on flat top AR is better,
DPMS AR-10 uses FNLAR magazines,
AR-10 design is easy to home-gunsmith,
Genuine H-K 91 chambers ruin brass,
DPMS parts routinely available, easy to come by,
Lots of custom builders and accurate uppers for AR-10,

No brainer AR is way to go.