Personnally I'm not a fan of the Sen'Jin Fetish.. I don't like the options for Slot 3..
Maybe the level 20 one is better than it sounds, but based on the tooltip it sounds like the Reflection ability, but you need to waste an extra round to do it..
Creepy Crate is pretty fun, I think it would be a viable choice.
A lot of people seem to enjoy the Ghostly Skull though, so I have a feeling most people will recommend upgrading that one.
Personnally I'm not a fan of getting stunned after my attack, so I think I'd go with the Crate, but that's me