One thing that I figured out a little to late is that resource producers don't scale linearly. Don't know how much exactly you get with each subsequent one, but it's definetly some sort of multiplier. Doesn't help that there's nowhere in the UI that shows your income. So I think the best strat would be to pick only water, upgrade loot rating a shitton of time, then reroll everything into crit producers, get a buch of crit rating and then reroll all producers again, this time into snow. All while picking every crit related combat item you can.
Too bad that this can only help in hindsight. I personally picked the producers evenly, which is probably the worst thing you can do.