If a user enables "Prefer this network" in the UI, the network will outrank other nearby wifi networks, even if they have a better signal or are more secure.  The user might not realize that an inferior network is being chosen due to the local setting.

The wifi strength icon in the system menu currently shows a lock badge for WPA networks.  Would it make sense to add another badge (maybe a heart = favorite = preferred) if the network has the preferred flag set?  And/or display the preferred status in the (i) tooltip?

(The selection logic is admittedly complex and opaque in general -- but feedback from the Chromebook Central forum leaders suggests that the preferred flag is a common source of user confusion.)