The MSI MEG Z890 ACE is the objective winner of this comparison, securing victory in nine out of fourteen evaluated specifications. Its most significant technical advantage is the inclusion of M.2 slots, which offer a 200% improvement over the Gigabyte B550 AORUS PRO AC. This substantial increase in storage connectivity provides a clear lead in hardware capacity, establishing the MSI board as the superior option for users requiring extensive high-speed drive support.

Users prioritizing modern storage expansion and high-end connectivity should choose the MSI MEG Z890 ACE for its superior M.2 slot count. Conversely, the Gigabyte B550 AORUS PRO AC remains the preferred choice for those who specifically require more PCIe x1 slots, where it maintains a 100% advantage over its competitor. Selecting between these two motherboards depends entirely on whether your build configuration demands more secondary expansion cards or a higher density of high-speed storage drives.