As they mentioned above Fighter torso is the ideal choice

Notes: The Slayer Helm is cheap OSRS GP gained after having completed Smoking Kills, a quest I strongly recommend you complete before starting Slayer seriously, when you earn 400 Slayer Points by completing tasks. One of the best ways to earn points is to do Mazchna's work in tasks 1-9. Then, the most difficult Slayer Master's task on task 10. I'd recommend Slug Menace for Proselyte and RFD for Barrows Gloves. Always make sure to use offensive prayers for any task you perform to speed up kills. The $ you make will be enough to break even. Make Farm Runs to reduce the loss gap, which will go away after some farm runs on that day.

As they mentioned above Fighter torso is the ideal choice, and you could use it in the moment if you wanted to acquire it. In terms of legs, I personally like Verac's skirt because of its prayer benefit (and manliness). Even if you don't pray for the whole time, you might as well take advantage of the base prayer points for superhuman strength (+10 percent strength in the first phase of your job is lovely) and the bonus prayer makes it all the more.

Regarding super sets strong and super attack are essential on any task, but super defenses are something you may want to carry if you feel you're getting hit a lot on one specific job. In any case, super defenses are very inexpensive compared to the other and their only issue with them is they take up inventory space.

Another thing you need to pick up is an DDS to buy OSRS gold equip your spec weapon (if you haven't already). It's inexpensive, and comes with a great offensive special that can minutely speed up your task (if anything , it gives you the satisfaction of getting two solid strikes).