Bandos chestplates and tassets. Falling in price, these are usually the top choices If you're in the market for cash. 12M for one piece and RS gold 12M for the next. They provide strength and prayer bonus.
I'm not an expert in helms, but if you're taking on the slayer, you'll want the full Slayer's helm because of its bonuses (likewise Salve amulet if it's relevant) as well as Verac's helm.
If you're looking for boots you'll want to stick to dragon. There are more comfortable boots, called "ragefire" I'm guessing, but I don't think you'd want to invest your bank on these. To get gloves, use barrows gloves from RFD, or buy OSRS gold perhaps gloves that are goliaths of the dominion tower.