If 4 SATA ports is enough (you don't need 6), slightly lower audio codec version is okay, slightly lower quality LAN controller is okay, do not need any USB3.1 ports, do not intend to 3-way CrossFire, do not need RGB ambient lighting, prefer a black + red motif (rather than all-gunmetal/grayish look), and 6 power phases is enough (instead of 8), then, the
MSI B350 Gaming Plus (at ~$90) is the more affordable and better value mobo.
MSI - B350 GAMING PLUS ATX AM4 Motherboard ($91.98 @ Newegg)
But, if you need all (or most) of the aforementioned features/ports/connections, then, the
Asus ROG Strix B350-F Gaming (at ~$116) should be your pick. It's up to your priorities and needs/wants if you can spend for the ~$26 difference for the above features.
Asus - STRIX B350-F GAMING ATX AM4 Motherboard ($116.98 @ Newegg)