I'm a big fan of Motul.
I switched to whatever Motul is Dino (Gearbox300??) and it shifted like butter. And still is after however many miles I put on it last summer. I'm not even going to change it this year unless I experience shifting issues.
I loved Motul gear oil in my RZ350 back in the day and loved it. I had completely forgotten about it.
I went to the Motul website: the Gear 300 is a synthetic 75W90 racing oil. The Gearbox 80w90 is a dino oil for "noisy transmissions". Both are rated for syncos and hypoid gears. The Gear 300 comes in an LS formulation for use with clutch-type LSDs