Cromoly is just a type of steel ( I think).
I have both a Steel tour bike and a AL road bike. Both are comfortable, but the steel tour is more so for really long rides, both because it is steel and because of its geometry. Longer wheel base, longer chain stays, more upright etc. Really soaks ups the bumps well.
My Al bike has a carbon fork and seatpost, so that may help some, but I find it is more fun to ride when I want to go fast. It has quciker handling and is ok for Century rides but not as smooth as the steel.
but there are exceptions to everything you will hear about steel vs carbon vs Alum.
A comfortable road bike can be made of any of these materials or a combination of them. Fit is more important.