Mosfet operating in cut off mode
The subthreshold current is very small and typically an uncontrolled parameter wrt. \$V_\mathrm{GS}\$, as it is strongly dependent on manufacturing tolerances and the temperature of the device. (Indeed, the threshold voltage also is only controlled within a limited range.) Hence I think that the most common usage is as the off state of a switch, where the long turn on/off time (due to gate capacitance) is counteracted by using MOSFET drivers that are capable of sourcing/sinking large currents. The ohmic mode is the typical on state for such a switch, rather than the active region, since in this case usually \$V_\mathrm{DS} &lt; V_\mathrm{GS} - V_\mathrm{threshold}\$ because of the small \$R_\mathrm{DS}\$ of the MOSFET. Here it behaves as a voltage-controlled resistor, although the resistance would be considered an undesirable quality in a switch and is therefore normally minimized.

This is not to say that an N-channel MOSFET in the cut-off mode cannot also be used as a voltage-controlled resistor, but it is not completely straightforward to do so. So, for the most common usage, switching seems to be the clear winner. One can easily see this by examining the datasheets of N-channel MOSFETS: the vast majority of them are recommended for switching applications, and most newer ones are trench-type devices that can be expected to display consistent properties between samples only when used for switching.