The ASRock Z890 Taichi wins in 6 out of 14 comparable specs, with 4 ties. Its biggest advantage is USB Type-C (200% better).
Z790 AORUS ELITE AX wins in 4 specs (MSRP: 53% better).
Recommendation
Choose Z890 Taichi if you want the best overall performance — especially usb type-c.
Choose Z790 AORUS ELITE AX if msrp matters more to you.