After 2.1 adjustments, the armorer leve seems to be the most time efficient with the raptor leather turn in being a close second.

The others, as you've said, have higher material costs or require zoning.

And what I like about this leve is that, even if we spread the word, it'll mostly likely result in the reduced cost of cobalt ore and cobalt ingots, which aren't too time consuming to get started anyway.