Verified answer

Dragons are the obvious answer. You can make good money from their bones and hide but they are often crowded.

I'd recommend working on your Slayer title while you train your combat. You can make good money from higher level slayer tasks so it's definitely worth leveling and you'll be training your attack at the same time. (2 skills for the price of 1 never hurts)

Making good money and xp are surely dragons, each d bone as for 9/14 are 5k, that's about 100k a load. Jus bring 2 sharks for backup on revenants (ghosts w/ mage attacks)

fight green or blue dragons.