I own a 1950 John Deere A with factory battery box seat, as well as 1946 Farmall M with original Farmall pipe spring seat, and a 1951 Farmall H with the optional Monroe seat (big tapered spring and a shock absorber).
The battery box seats on the Deere letter series 2 cylinders lack a suspension system. In other words the cushion foam is all you got. That said they are decently comfortable as long as the terrain does not get too rough. The rollamatic front end helps smooth the ride a bit too. Now once you go with a Deere 50,60,70 or newer 2 cylinder then you get a float ride seat with suspension. The rubber torsion springs break frequently though....
No way would I trade my M off due to not liking the seat. People have mounted Deere battery box seats on their Farmalls (I know sacriligous). After market seats can be mounted as well rather easily.
Over all, I like both my Farmall M and my Deere model A. The Farmall is much smoother on PTO loads and the Deere has a better selection of gear speeds (only the 1950, 1951, and 1952 models have the better single stick tranny though IMOP). That said, if I could keep only one of them it would be the Farmall M.