I don't generally have trouble with the multiple waistbands digging in thing. I could definitely see bibs being more comfortable for higher effort stuff, longer xc-ish rides, road rides, longer gravel rides, etc, though. for me, the difference would probably be more of a general rubbing thing. but on the vast majority of my rides, I don't experience that, either.
I usually feel more comfortable with clothes that tend to feel more like regular clothes on most of my rides. of course, getting the fit and fabrics right for mtb riding is essential for that to actually work.