MTA is good for cash. Don't know the experience per hour, but the alching room is very high I heard.
Alching itself, around 70k experience an hour. I did maple longbow (u). Will make a loss.
Stun, cheaper option. But requires more clicking.
Ice bursting. Good experience, do it at rock crabs or rock lobsters to gather charms. Will cost a lot however.
Soul Wars. No cost. Just use zeal on magic.