Is an op amp voltage follower better than one made with discrete (MOS)FETs?
Yes opamps are better. the opamp is two components: the opamp and the bypass capacitor.
the mosfet follower is 5 components.

Additionally, opamps have lower offset voltages and better linearity, and better accuracy because of large amounts of negative feedback.

The only case where I would use a discrete follower would be with high voltages. Because it is more difficult to get high-voltage opamps that are cheap.