I bought the Onkyo a while back. I need XLR connectivity, so the NAD was a non-starter. Also, a new NAD t187 sells (IIRC) for about $3K, while the Onkyo can be found new for app. half that price. Together, the delta in price and feature set might eplain why you don't see these two units compared/cross-shopped more often.
Marty