It depends...
Miykael--on the rifle, and on the intent.
My high-falutin' target rifles all travel in hard cases. Too much work goes into zeroing them to have them bumped.
My hunting rifles go in hard cases for transport (usually by truck or station wagon) and in soft cases for convenience during the hunt (when they will be cased and uncased several times/day)--IF I can scare up enough hard cases for them.
My so-what rifles, for plinking and such, always get a soft case, and they'd travel in gunny sacks if it were legal. (In my state it has to be enclosed "in a case manufactured for the purpose of containing a firearm" or some such nonsense, for transport.)
Rather much the same rules apply for my shotguns and handguns.
Now, archery equipment, OTOH, always gets hard cases--There are just too many fragile bits sticking out in too many directions!! And a crossbow case is the only thing that is more awkward to pack into the truck, than a French horn case, but there you are.
Then, the dogs can jump up on the load, we can bounce down a dirt lane, it can get dusty or rain can blow in, and there are no worries.