I actually used an Archer C7 before the DIR-860L, although in a different home, so no direct comparison unfortunately. But my general feeling says that the range on 2.4ghz is much better on the DIR-860L. Speeds were comparable between the two routers, although I've read that the DIR-860L doesn't like crowded spectrums. I can't comment on that myself, since the 2.4ghz spectrum is still relatively clean in my new place.
On the 5ghz radio, I believe the Archer had better range. I can't really compare the speeds, since my old internet connection with the Archer was a 200 Mbit connection, which the 5ghz was able to handle at full speeds. I never tried local speed tests with the Archer. The DIR-860L does 200-300 Mbit for me depending on range and obstacles between the client and router.
The Archer C7 does support 3 spatial streams instead of 2 like the DIR-860L does. So if you client supports that, the Archer C7 is probably faster on 5ghz. I don't any 3 stream clients myself, so for me it was a moot point.