I really like Schwalbe Almotion in 700x40. The casing is based on motorcycle tyre technology, supposed to lower the rolling resistance by changing orientation of casing laminates (I don't have any idea what Schwalbe is claiming, I note they make motorcycle tyres).

It's my only pair of 40mm/600gm road tyres so I can't make a valid A/B comparison to other heavy/fat road tyres. Having said that, they riding really smooth and roll forever. They're a little too slow for club based gravel grinding but for commuting and recreational riding they're all I ride.

(My other wheelset has 32mm Paselas and I am starting to really dislike riding them esp after cruising on the luxurious 40mms.)

I've been riding them ~1.5 yr with no flats, ~2000 miles. Colorado with goatheads, lots of road shoulder glass and super abrasive feldspar sand. Freaking bullet proof.