Looking at the specs for wireless (not wired connections), RT-AX88U looks like the clear winner for speed in a normal household of ~10-15 connected devices. Is this correct?
RT-AX88U (
https://www.asus.com/us/Networking/RT-AX88U/)
802.11ax 4x4 = 6000Mbps
802.11ac 4x4 = 2600Mbps
RT-AX89X (
https://www.asus.com/us/Networking/RT-AX89X/)
802.11ax 8x8 = 4800Mbps
802.11ac 4x4 = 1733Mbps
I believe the 8x8 solution of the qualcomm chip functions as two 4x4 chips in parallel using similar channels, but i'm not exactly sure. "QCN5054" is apparently a 4x4 chip in some devices.
The AX performance of these two manufacturers are going to be significantly different, though. The Qualcomm variation apparently has much higher throughput from early testing of a RAX120, but recent Broadcom/ASUS/NETGEAR updates may have changed that. NETGEAR markets their qualcomm solution with much higher range vs the Broadcom chip in the RAX80.
The AX88u is a 4800 5g (160 mhz) + 1152 2.4g (40 mhz) device with two 4x4 radios on AX. Same for RAX80.
On AC it does 4333 5g (160 mhz + a non standard QAM-1024) + Whatever QAM modulation was added for the 2.4G in terms of wireless N. Anywhere from 600 (QAM-64) to non standard 800 (QAM-256).
AX89X is apparently soft limited to 4800mbps 5g and maybe disabling half its MIMO to run 160mhz modes as the max theoretical spec should be 9600 mbps for the 8x8 alone (with 160mhz channels).
The AC speed looks limited to 4x4 on QAM-1024 with 160mhz channels.. That or 80mhz with full 8x8 MIMO coverage.
I would say the Qualcomm solutions are better in terms of outside looking in, but It really depends on your needs and what you want out of firmware/support etc.
Edit:
http://bbs.ntpcb.com/read.php?tid-142430.html heres a picture of a RAX 120. Theres two 4x4 5054 chips. Surprised there isn't a AX6000 solution with just one 4x4 to compete with RAX80/88U. I know charter has an early sample PCB of a single 4x4 + 4x4 5g and 2.4G radio, but thats all I'm aware of. Maybe 160mhz requires disabling half the MIMO of each chip? I'd assume that nerfs the overall range though.. Spec would def be lower than "AX6000" too if that was true. More or less "AX3600"
RT-AX89X is a dual-band router. You can achieve better throughput to more devices with GT-AX11000 tri-band.
While typically true, its a little different on the AX89X given the "8x8" or dual 4x4 5G mimo. They're probably fairly equal unless youre exclusively running 160mhz clients... which may benefit from a triband solution like the AX11000 more so.