Cost wise Rockoil is quite good and slightly cheaper than Liquimoli. Penrite is 5L for almost the same price so it's cheaper cost per liter.Got suggestions?
Anti-shearing and temperature stability wise Penrite, Rockoil and Royal Purple is awesome.
Sometime ago there was this brand Adnoc that had a pretty good full syn range called "Image". It didn't have great base stock but the additives in it were pretty incredible. Pity this brand is hard to come by now.
I've tried dozens of oils but haven't really put all the oils through heavy duty tests.