right now ? probably some barbarian . Sigma will hopefuly make the summoner necro great again and put him back on the top of the summoners list as i don't think it's normal to have a summoner barb better than a summoner necro . the sorceress summoner is also close enough on third place . there are clues pointing that the summoner necro will be reworked
it's probably meant to be written as vesseldin, not neutral. used to be a neutral spec. clearly is using the shadow tree, which keeps neutral, but speccing superbeast makes it unholy, yes.
and then you dont have both effects of Life and death i think ..... but without Superbeast and any other holy or unholy skill you should have them both .... right?