Wireless Performance - more
The 5 GHz downlink profile shows the ACS with much higher starting throughput than the other two routers. This clearly gives it an advantage in total average throughput. From 15 dB attenuation on, however, the AC and ACS track very closely.
5 GHz Downlink Throughput vs. Attenuation
For 5 GHz uplink, the ACS again starts off with the highest throughput of the group, then starts its decline. The AC's curve jumps around a lot, but starting at 24 dB attenuation tends to track the ACS'. The Broadcom-based EA6900 has the best throughput starting at 21 dB attenuation.
5 GHz Uplink Throughput vs. Attenuation
The WRT1900ACS ranks #7 out of twelve tested AC1900 routers; a pretty disappointing showing. Comparing the Router Ranker Performance Summaries for both products shows sub-ranking details to explain the difference. The sub-ranks tell a Tale Of Two Routers story, with the ACS besting the AC in the 5 GHz band, but coming in a distant second in 2.4 GHz. Wired router ranking cancels out with a tie at #3.
WRT1900ACS Ranker Performance Summary comparison
The WRT1900ACS' brightest spot continures to be storage performance. Both the original WRT1900AC and WRT1900ACS stand above all other wireless routers we've tested of any class in our large sequential filecopy test.
I hate to say it, but Linksys appears to have taken a step backward with the WRT1900ACS, at least for 2.4 GHz performance. If you like everything else about the WRT1900, then grab an AC while you can.
Once they're gone, your best option in a Linksys AC1900 class router will be the EA6900. With a #3 performance rank and available for as little as $120 new and $100 refurbished direct from Linksys, it currently ranks #1 in bang for the buck in AC1900 class routers.