I can't actually speak toward the WRT 1900ACS. I do own quite a few R6700v1/R7000/R7200s. Their Broadcom chipset is ok as a packet forwarder, though even there it is CPU bound long before reaching the link speed except for ethernet-to-ethernet switching. It is notably terrible for any packets the device has to itself source or consume. So Samba, or VPN, or anything like soaks up your CPU.
My experience has been such that I now stay away from Broadcom as much as I possibly can.
Ack! So sorry. Right. That's the Walmart clone of the R6700v2, not the v1. That's a very different beast. I have only one of those which was, sadly, languishing in a drawer until just a few weeks ago. It will never languish again. Fantastic unit. I cannot speak highly enough of them. The MIPS32r2 880MHz processor is a little light, and even megahertz-for-megahertz is only about 80% as fast as ARM devices. But Mediatek offloads almost all the data movement into hardware acceleration. The MT7615 Wi-Fi chip, for example, has its own coprocessor on board for data moving. So the main CPU doesn't even break a sweat most of the time. It will source/consume data at the full wire speed.
Handles symmetrical Gb Fiber here well, without SQM enabled. (routing)
Handles DSL, Cable, etc. w/ SQM enabled well. (routing)
Handles 5-10 total WiFi connected endpoints, on both 2.4 / 5 Ghz networks well (WiFi)
Handles banIP, Bandwidth Monitor, SQM Qos, OpenVPN, Advanced Reboot, etc., well.
Runtime is in weeks -> months. Have to remind myself every month to (reboot / reset) the (3) routers here. Usual home bandwidth consumption is 400-600 GB / month. (IPTV, w/ wireless endpoints). Client installed units run months w/o issue, I try to visit on-site & reset every 45-60 days / as needed.
WiFi Range is fine on this router. As good as (but not better than) the other 1900ACS offerings from this time frame by other vendors. It will not 'magically' extend coverage, 'travel faster than a speeding bullet', 'leap tall buildings', etc. * If extended range coverage is a primary concern: consider using (multiple) AP endpoints -> and logically extending the WiFi network. ... This is a capable circa-2015 WiFi router: not a Tri-band Mesh WiFi here.
The Netgear R7800 is also a capable router, and well supported here. I support a few at client sites, WiFi range is slightly better on the Netgear, in my experience.
Either router will be a solid choice, WRT1900ACS or R7800.
No experience w/ the R7200 router. Hope the feedback is helpful.