I know 100% Raw Fish, 50% Coal used to be the best option, but shortly after the high-level Herblore release it turned to 100% Herbs and 50% Raw fish.

But I've been away for some time and I'm wondering, monetary-wise, which is currently the best investment?

 

Thanks in advance.

Herbs Fish is still the best

I do 10 herb 5 maples. I usually get some nice seeds here and there.

The best is 10 herbs. The other 5 workers, which you should have, have 2 options. Raw fish are good for a set amount of gp to get from them. With maples it varies from what kind of seeds you get in the nests as that is where most of the money come from, but the crushed nests do sell nicely.

 

I personally have it set on 10 herbs and 5 raw fish, it usually gets me ~2m after i sell them off not counting what it uses each week. But i also keep some herbs to make into potions.