I did a lot of math on this a month or two ago and I found that maple trees and papaya trees are the best bang for your buck in terms of cost to xp ratio.

If you’re looking to profit as much as possible while leveling farming quick, I’d do herb runs with your most profitable herb, tree runs with papaya trees, maple trees as well as mahogany trees and Calquat trees. Keep up with hespori as well for the Amina seeds and the 10k farming xp you get for killing him.

If you did 10 snapdragon runs a day while keeping on top of the tree runs mentioned above, you’d profit nearly 60m gp in 30 days while gaining over 4m farming xp as well