Torag's gives the best defence in the game, but it can be upped if you use a shield instead, like RG said.
Torag's helm, plate and legs.
Gnome, Fury, or Glory
Cape of achievement, obby cape or lava cape
Barrows or Dragon gloves, spiky black d hide if you can't get rfd gloves.
Rune boots
lunar ring (tid bit of mage def, Fremminik rings may give melee def i don't know)
Dragon square or crystal shield
Dragon long, scimmy, or dagger.
That gives the best defence in the game, I do not know of a better combination.
Ofcourse doing the best parts of that combo requires around 7m for everything but that's why I gave other options also.
I hope this helps ya.
