The main difference for me in saddle preference on roads vs gravel (and, more of the time, cyclocross) is that I can tolerate many more different saddle shapes on the off-road bike. My road position is much lower and I have more forward pelvic tilt, so I really need pressure relief features and just the right shape to be comfortable. Currently my favorite saddle is the Selle Italia SLR Flow and I actually bought a spare against the fear that the shape will change at some point. Off-road, the saddle needs to be easy to move back and forth on, and not too large or pointy to avoid snagging shorts when dismounting/remounting or when getting behind it on a steep descent. I don’t have any different needs for padding. On road or off, my preference for the saddle is to have some padding, but for it to be thin and firm. Chamois handles most of the cushioning duty. The saddle needs to have enough to take the edge off but not enough to sink into.