Only three things matter: good fit, good fit, and good fit.

Some companies have frame geometry that varies from the industry "average" in some way. Push the seat back closer to the rear wheel. Longer top tubes for a given size. Or the opposite.

Mountain bikes, compared to the "average" road bike, have a long wheelbase, long chainstays, and relaxed geometry. The road bikes that share those features are the road bikes that are designed for loaded touring. Unfortunately, loaded touring bikes have become rare (Trek offers just one) and tend to be expensive.

As the wheelbase and chainstays get shorter, the geometry becomes more upright, moving the seatpost closer to the front wheels. The rider begins to feel every bump in the road...he suffers...by George, his suffering makes him a true roadie.

Most bike branks have on-line spec sheets. If you want a road bike that rides like a mountain bike, look for the models with the longest wheel base. Those models will also have more relaxed seat tube and head tube angles.

And, yes, a good steel frame and fork has a ride quality that is far superior to that of an aluminum frame and aluminum fork. But, like loaded tourers, bikes that have both a high quality steel frame and fork have become rare and expensive.