One thing I will say about Arnold. He never tries to wear anything that makes himself look better. If he's skinny or fat he's wears clothes that show he's skinny or fat. He seems totally comfortable in his own skin.
Stallone on the other hand does everything to make himself look as good as possible. High rise shoes, muscleshirts with arms flexed and pumped, even in the new films his little arms are flexed away.
Checkout this pic. Arold relaxed in a Polo shirt, no socks, flat shoes, looking at porking the tart sitting down. Stallone with his 3 inch moonboots, little muscleshirt and badass bandanna. Bicep flexed for the photo. Franco standing there with his wee withered legs without a care.