Ultimately, all of them, but if you aren't sure- start by aiming to get each one to level 30, or 50 and finding what you like. Then go for a 99, a 120 and eventually, a 200m! The skilling has no end as long as it's fun!
23 200ms. Founder of Jamandy52 skilling clan. Favorite skill: Construction. Love skilling. Love minigames.
Working on 200m Divination atm. PM for effigies assists, and for tips when skilling. World 70.