Combine the two and powerslay! This means you'll use your most powerful att/str booster prayers and super pots for your tasks RS Gold, a cannon in addition if you'd like to/can afford. This can lead to up to 100k exp per hour at higher levels, which is more or less than armoured zombies and bandits. It also means you don't risk appearing as ridiculous as a person with 70 slayer.
Gear must include: Barrows gloves, from RFD. Dragon boots. Full slayer helm, black mask until you get it. Make sure to proselytize armour when you use prayers, and barrows if don't. Whip, attempt to make an uncontrollable rapier as fast as you are able to. Dragon defender, antidragon shield for Dragon-related tasks (DFS is unnecessary, do not try to use one).
Amulet of glory, try to obtain one when you can. Ardougne cape 3 or the soulwars cape. While it's intriguing does it not defeat the goal of slaying? A big part of learning to Slayer is something new to finish every job, and that's sure good. However, isn't the goal to make money? I'm pretty sure eventually prayer potions would rise in costs to the point of losing money, wouldn't you think?
Thank you for all the suggestions everyone. Even with prayer potions , one are likely to profit from slayer as they are quite affordable. If you only drop them, you will make money, and if you don't have that then you should consider purchasing Slayer Dart's runes at the slayer master's shop for 35 points to slayer (you get 36 points when you complete two tasks at Kuradel) will cost you around 70k Cheap OSRS Fire Cape, which is a decent amount and can add up to some decent money if spending the money instead of blocking or cancelling activities.