Needs to have good drops and in multicombat area

Dags under lighthouse drop charms/caskets.

Slayer is the only time I would reccomend a cannon.

apparently ice trolls are good to cannon but i dont know if it was nerf or not

Wallasalkis are good, they give like 80-90% return in profit and sometime you will make profit which will pay for the times you lose some money. I did this for 75-80 and it was worth it. Its about 75-80k exp which is pretty good since you will lose barely any money.

As Kent said, it's only going to get a return if you do slayer. If money is not a problem, dagganoths are alright - they drop alot of gold charms, high level farming seeds (snapdragon, ranarr etc..), and caskets,sometimes lvl 2 clue scrolls too.