Chaotic rapier. The most powerful melee weapon you can use one hand you acquire after a period of OSRS gold dungeoneering it requires at minimum 80 dunge in order to purchase it with the dunge reward system. Most chaotic weapons are most powerful in their class.

Bandos chestplates and tassets. Prices are dropping, but these are usually the top choices if you've got some cash. 12M for one piece and 12M for the next. They give a extra strength and prayer reward.

I'm not an expert on an helm, but if taking on the slayer, you'll want the complete Slayer's helm because of its bonuses (likewise Salve amulet if it's pertinent) and the helm that Verac has. For boots, you'll probably prefer to stick with dragon. There are other boots that are better, named "ragefire" I'm guessing however, I'm not sure you'd want to invest your money on these. For gloves, either barrows gloves from RFD or possibly the goliath gloves that are in The Tower of Dominions.

Goliaths will require you to have completed a lot of quests and lots of arcade-style combat in an immense tower full of quest bosses. A thing you may find once you've finished your questing I'm sure. To get the ring, there's an extremely nice free ring that you can obtain when you complete "A return to stone" (I believe that's the name the quest is called).

It starts in TzHaar city, near its birth pool. The fremmenik attack bonus ring's features, and several very nice portable teleports to use, and combat bonuses to fight the tzhaar. Then you could purchase the Berserker ring, which gives an extra strength bonus. Or you could get the explorer's ringthat gives you free alchemy spells every day. You might want to purchase an Onyx band and have it be infused in bringing armies to rs07 fire cape service battle. Go to Google if want more detail.