I looked at the Archer C8 but decided against it. Third-party firmware support did not look promising at the time, and the stock firmware was meh. RT-AC56 is also dual band, and I paid $50 for it off of Kijiji
Yes, I looked before purchase and (at least at the time) neither Tomato nor DDWRT were supported, however the sales person Assured me that the stock firmware was plenty capable once upgraded – sure enough with the firmware update that I applied after getting home...I'm wanting for nothing and performance is stellar.
The one month I mentioned above where I put 1.7TB through my internet connection, that all went through the C8 without a reboot, not to mention my in house intranet traffic as well. With my houses level of traffic I used to have to reboot the Cisco routers at least once every week or two otherwise they'd either slowly lose throughput, or eventually crash/lockup.
I sound like a TP-Link employee here, not the case, just have had a really great experience with it, and the 2 year warranty is reassuring. The form factor stinks, but well, not much I can do about that, and as mentioned, likely less of an issue for most people.