As far as quality they are probably equal.
Saito fans will tell you it is best. OS fans will tell you the opposite.
I'm an OS fan, probably because OS is the overwhelming favorite at our club. A few 'new' members have introduced us to Saito but they are still fairly uncommon.
Saito still expels excess oil into the air through a crankcase vent. OS routes that oil into the cylinder so it relubes a little and is blown out the exhaust.