It’s probably a wash, in terms of what you’d actually see in the numbers, although theoretically the narrower tire should save a bit in terms of aerodynamic drag. Probably that theoretical difference is easily eaten up between factors like tread pattern difference, rim size/shape, and frame design elements.

If maxing out potential gains is what you’re after, go 25mm width rubber in this case.

As for which tire specifically, have a gander at BicycleRollingResistance and grab any of the top tires:

https://www.bicyclerollingresistance...d-bike-reviews

I’m a fan of the Michelin Power Cup R TLR tires, but more for overall road performance than just straightline speed. The Vittoria Corsa Speed TLR is the champ (by the numbers), though.