I use Motul 300V fully synth in mine.
I thought it was supposed to be one of the dearest brands around, but I paid 30 quid for 5 litres at my local bike shop.*
* Fair play to Phoenix Motorcycles, Trowbridge. They hadn't got any 5 litre cans left, but decanted 5 l for me out of the big tub in their workshop. Just said, "Have got got an empty can at home?", and I nipped home and fetched a can. Worked out a bit cheaper, too.
I know you could say that otherwise, they'd lose a sale, but I'm sure a lot of shops wouldn't have been bothered.