Linear Regulator: MOSFET vs BJT
In a linear regulator, switching speed isn't a consideration.  However, BJT base current can be.  There's no steady-state gate current in a MOSFET so a MOSFET can be lower loss.

Also, a MOSFET in the on state looks resistive, so the dropout voltage can be very small at low currents.  A BJT will saturate and may lead to higher dropout voltage at low currents.

At higher currents a BJT can suffer from low current gain.

All of these things can be mitigated by proper design, but they are definitely considerations when choosing a pass element.