The MSI MAG X870 TOMAHAWK WIFI wins in 8 out of 14 comparable specs, with 4 ties. Its biggest advantage is USB Type-C (100% better).
B760 AORUS ELITE AX wins in 2 specs (PCIe x16 Slots: 50% better).
Recommendation
Choose MAG X870 TOMAHAWK WIFI if you want the best overall performance — especially usb type-c.
Choose B760 AORUS ELITE AX if pcie x16 slots matters more to you.
