I've ran panaracer gravelking in both 28 and 32s for several yrs now. I don't find there is much rolling resistance feel between the two but the comfort level in the rough stuff does feel different. They are soft and grippy tires in the turns w/ decent/good flat protection.
If you can fit it, 32 should be way to go. I run the slick(file thread version) and they are about $35 on amazon prime.
https://www.panaracer.com/lineup/gravel.html