Combine the two and powerslay! It follows that you simply use your very best att/str boosting prayers and super pots on your own tasks, a cannon as well in the event that you would like to/can afford to. This can get you upwards of 100k exp/hr at higher levels, which can be as much or OSRS gold more than armoured zombies and bandits, and you also avoid looking foolish as a 138 using 70 slayer.

Gear ought to be: Barrows gloves, out of RFD. Dragon boots. Complete slayer helm, black mask until you obtain it. Proselyte armour should you use prayers, barrows if you don't. Whip, attempt to receive a chaotic rapier as soon as possible. Dragon defender, antidragon protect for dragon tasks (DFS is overkill, don't bother with one). Amulet of glory, attempt to acquire a fury as soon as you can. Ardougne cape 3, or soulwars cape.

While that does seem intriguing, doesn't that defeat the purpose of slaying? Part of the enjoyment of training Slayer is something new to kill every task, sure, nice. I'm pretty sure eventually prayer potions would run up the charge to where I'm losing money, wouldn't it? By the way, thanks to the information everyone.

Even with prayer potions you'll likely gain from slayer, they are rather cheap. From the drops alone you should gain, and if you do not have that then buying Slayer Dart runes from the slayer master for 35 slayer points (you get 36 for RuneScape gold buy performing two jobs from Kuradel) gets you around ~70k that is decent and may add up to a good cash if you spend your money on this rather than cancelling or obstructing tasks.