The reason why I put it more into herbs is because there is no guarantee that you will get a lot of tree seeds. Sure there is a chance, but there's no guarantee. At least with herbs if you get a few hundred, that's a nice profit. However, with that being said, I still find it worth it putting a good amount into maples as well because you do end up getting a fair profit with seeds anyway. I've just found that I've gotten more profit with herbs than tree seeds unless I get really lucky. Crushed nests are usually for brews, but with the large variety of potions available compared to that one secondary ingredient, I would feel safer doing herbs.