From a after action clean up perspective leather, when granny visits and smiles and gives you that knowing look because she saw the stain on the sofa it gets a little uncomfortable. Fabric is great in the hot weather lets your skin breath and you don't weld yourself seat.
At least it's not vinyl, the rise n recline chair I use .for my treatment (hospital issue) is vinyl, it's easy to clean any blood off, but it's literally a pain in the arse to sit on. Even covered with an old bedspread doubled it still draws the sweat.