I'd say mining, but things you enjoy aren't so tedious. I guess I'll have to vote Runecrafting. It's just as slow, maybe more (I don't know; I don't runecraft that much), my reasoning is the little amount of experience you actually get and the long distances you have to run back and forth, repeatedly. Granted, mining is in the one place and it's just mine two, drop two, mine two, drop two, competition comes, they beat you, you are hindered. There's not nearly as much to manage in comparison to restoring run energy, conserving space and finding the shortest route when runecrafting. Ok, maybe I can't toss up between the two. Maybe... put me down for both? I have next to no experience of agility (pun ABSOLUTELY intended!), so I shan't say.