The ASUS ROG MAXIMUS Z890 EXTREME wins in 8 out of 14 comparable specs, with 3 ties. Its biggest advantage is USB Type-C (300% better).
MAG B650 TOMAHAWK WIFI wins in 3 specs (PCIe x1 Slots: 100% better).
Recommendation
Choose ROG MAXIMUS Z890 EXTREME if you want the best overall performance — especially usb type-c.
Choose MAG B650 TOMAHAWK WIFI if pcie x1 slots matters more to you.
