I would rather see Li-S be used in planes where inspections are common unlike cars.

For grid storage neither is ideal, as you really want to decouple (dis)charging from capacity. Subterranean normal pressure hydrogen storage (using geological structures like salt caves) or flow batteries seem more promising for that reason.

Having a hydrogen economy is overall pretty inefficient. I think it's largely a dead end. We do not need multi-year energy storage. Seasonal storage is needed at most. Lithium-ion batteries have self-discharge rates of around 2% per month. Even if the batteries lose ~10% over a few months that's an acceptable loss and is superior to the inefficiencies inherent in hydrogen production via electrolysis and the subsequent use of stored hydrogen via fuel-cells — which require platinum-group metals.