If you do not wish to do any quests I'll recommend doing 1-44 fire runes or airs.
(Doesn't really matter as you're botting it, right?)
44-99 nature runes using a spirit graahk, 57 summoning required.
But if you want to do any quests you should do 1-66 zmi and 66-99 deaths via abbys. This requires a lot of questing though. Your choice. Could do some bloods aswell, whatever is more profiting at that moment.
-One And Only-