I've commuted on a roady, a steel big tire bikepacking bike (basically a hardtail MTB) and now a gravel bike. I'd say the tires on gravel bikes tend to be the best compromise between comfort you get from a big volume tire, and the speed of a road or commute tire. They can run pretty high pressures, which is the biggest factor for rolling resistance, and they're pretty skinny relative to MTB tires.
For me, the minute rolling resistance tradeoff between the gravel tire and a commute tire is worth it. The road and bike network here kinda suck for smoothness, I'd rattle apart if I ran a road tire.
Thanks for the feedback! I've not had the occasion to try gravel tires.
For me, the main reason to use road tires is grip on asphalt, not rolling resistance improvment. On your commute, you may need to stop in an instant, and more grip = quicker stop = safer (I've had a few close calls, especially downhill under rain).
Obviously, that's also dependent on your regular commute road condition.
Braking is the main reason I love gravel tyres for commuting: their increased size means a larger contact patch which directly translates into a shorter stop (as stopping on skinny tyres with disc brakes is typically traction-limited).
The tyres on my gravel bike look just like fat road tyres: no knobs.
