For a hardtail bike a very good all around tire is the Rekon Race tire in the front and in the rear. Not as aggressive at tread and provides higher rolling speed that most other mountain bike tires. For a gravel bike with rims that can take a 700x42 tire the Specialized Pathfinder Pro 2Bliss is a good all around tire and not terribly expensive at $45-$55.

https://www.bicyclerollingresistance...pathfinder-pro