I used to always use 23x700c tyres on my road bike, but with the advancing years of an aging body i started to find them to jarring.
I now use 28x700c tyres and I find them much more comfortable and "dare I say it" from face value, rolling resistance is better.I think if I where to go wider the comfort level would be even better but I think rolling resistance would increase to.
This month I've been enjoying using a fat Ebike with 26x4" tyres..
The comfort level is unrivalled and the horrendous pot holes down the remote lanes where I cycle are no longer an obstacle.They make cycling (in my view) so much safer, because I'm not having to treat the roads like a slalom course avoiding the pot holes that could potentially throw me off or destroy my wheels.
The rolling resistance on them though is very heavy.Cycling without pedal assist is like cycling through thick treacle.