[Ferok]

Best in what way? Epic has great stats and a clicky DoT, as far as I know there's nothing quite like that.

If you're looking for the best ratio on a dropable spear, Slime Coated Harpoon.
If you're looking for the best clicky effect on a droppable shaman weapon, Fungi Staff is probably your best bet.
If you're looking for the best proc, the Barbarian Spiritist Hammer probably is your friend if you're a Barbarian (procs at 30).