Seeking best option to add AiMesh to an existing Asus RT-AC88U?

Hi everyone,

We've had a Asus RT-AC88U for 6 months now and we have been impressed by its speed.
However, as expected, it cannot cover a 5 bedroom, 3 storey brick house.

I'm thinking to make the RT-AC88U the base unit and add another 2 or even 3 AiMesh units.

All 8 ports from the RT-AC88U are wired directly to rooms throughout the house, so I assume it makes sense to wire the AiMesh additional units?

We're looking at the Asus XD4, XT8 or AX6100.

What Asus units would you recommend please? And what are the trade off for each please?

Jon ("Wireless novice!")