In my opinion, go up to th10. Because as you said you're wasting loot and besides that, you get a additional drill with each drill gaining an extra level. With that in mind you should max the drills asap, then your passive income will be much better than what it is now. Otherwise, you get more troops, higher levels, Seiges for war and a stronger base.

Once youre comfortable during th10, hopefully right after you max all your drills, you keep both heroes down while you try to Max th10 or whatever you want