I still believe authoring can earn you the most.
Sometimes I look at Steem too much from my own perspective. And the more SP you have, obviously the more curation you can earn and I compare that to my own blogging efforts and conclude that curation is the stability factor.
Maybe, that's not always fair.
For some, it will indeed be authoring but the content will most likely have to be of better 'quality' than others to receive rewards and those rewards will have to come from SP holders and you don't know if you will always get the votes (hence it's not always stable).
But all of it beats the bots as we seen before.