Which is better as a switch?
What you say is true only for low to moderate currents, up to, say, 100 A or so.

The VCE(SAT) of a BJT is more or less constant, regardless of current, assuming of course, that the transistor is robust enought to handle the current in the first place.

On the other hand, the channel of a full-on MOSFET functions as a constant resistance. This resistance can be very low (miiliohms), but at high currents, it can still result in a higher voltage drop &mdash; and higher power dissipation &mdash; than the equivalent BJT.

This is why the IGBT, which combines the best features of a MOSFET and a BJT, is so popular in the highest-power applications.