Helltide event still more rewarding becaus the gobby items from bags not tradable.
But if you really want to get a LOT of items solo self found make up a bunch of extra shrine maps camp greed shrines get 10-20 bags a shrine on top of the gobby loots. In group even more if you communicate.
Oh and s3 event was garbage too. You got nothing for it but cosmetics which is effectively nothing.