Adaptive QoS is far more than just marketing BS. When the RT-AC87U was released, I remember mentionning on these forums that IMHO, the biggest feature the RT-AC87U brought was not its 4x4 or future MU-MIMO support, but everything related to Trend Micro's DPI engine, including Adaptive QoS.
Standard QoS is only able to classify traffic based on IP, MAC, port and amount of transferred data, and it requires you to disable NAT acceleration, which means those older MIPS-based routers are limited to about 150 Mbps.
Adaptive QoS uses DPI to classify traffic, meaning it can actually examine the type of traffic, but also the specific destination. That allows it to do a far more accurate classification than legacy port/IPbased classification. In addition to that, it can work with NAT acceleration enabled, which means you can reach well beyond 650 Mbps with Adaptive QoS enabled (that was the result I got when I benchmarked an RT-AC56U using it back when Asus first added it).
If you want to see how precise Trend Micro's DPI engine can get, turn on Apps Analysis on the Adaptive Bandwidth page, and expand the list of protocols detected on one of your computers. It's able, for example, to distinguish Youtube traffic out of the rest of the web traffic, meaning it can easily priorize your Youtube streaming.
Adaptive QoS is closer to L7-based QoS as used by some on Tomato, only with far, far more accurate rulesets than those outdated L7 filters, and requiring very little configuration.
So if only for its ability to work with CTF enabled, Adaptive QoS is superior to the old method by far and large.