Wireless Performance - more
For 2.4 GHz downlink, the C8 starts midway between the other two routers, but comes out on top from 33 to 57 dB of attenuation. Only the ASUS makes it all the way out to 63 dB, but at essentially unusable throughput.
2.4 GHz Downlink Throughput vs. Attenuation
Unfortunately, the 2.4 GHz uplink plot shows the C8 as the lowest performer of the group, although it makes it to 60 dB of attenuation vs. the C7 V2's 57. This plot illustrates one of the the things that drives router shoppers crazy, i.e. you can't find a router that is best on both bands and both up and downlink.
2.4 GHz Uplink Throughput vs. Attenuation
The 5 GHz downlink plot shows the C8 on a very much middle-of-the pack course. My call here is that you'd be hard-pressed to find a significant difference among the three products in real world use.
5 GHz Downlink Throughput vs. Attenuation
For 5 GHz uplink, the result is about the same as downlink. All three products are essentially the same.
5 GHz Uplink Throughput vs. Attenuation
TP-LINK has had a pretty strong seller with the Archer C7, primarily due to its sub-$100 price. The C8 doesn't have the same price advantage, however. At currently around $140, the C8 is closer to the ASUS RT-AC66U ($157) and NETGEAR R6300 V2 ($148) and will have to rely more on its features and performance to make the sale.
Fortunately, AC1750 technology has matured and significant performance differences are hard to come by among products with the same chipsets. Since the Archer C8 is based on Broadcom's second generation BCM4709 processor, you don't have to worry about buying an older generation router.
In the end, the Archer C8 doesn't stand out from the pack of AC1750 class routers. But it should serve you as well as its better-known competitors and save you a little money, too.