I would check previous topics on this matter, there is no right or wrong answer or clearly defined *uber* class.
My personal favor is soul taker for awesome debuff and future transfer pain in next update.
Tried storm screamer and didn't really liked it, debuff for activating buster spell were landing pretty randomly even on mobs. Alto future patch will bring nice Matk boost, at expense of the MP, but that part is pretty much useless, since feoh don't run out of MP unless using arcane barrier with archer party targeting you.
You just have to decide for yourself what you like more, there is no mommy to tell you right choice 'coz there isn't one.
Depends on how you play really. Soultaker and Soul Hound are obviously being balanced with PvP in mind while they others are a bit more PvE focused. Lindvior isn't really "the Soultaker" update. Epeisodion is the update that will truly give it its previous flavor, but Transfer Pain/Servitor's usefulness is debateable since Archers and Nukers now use a ton of AoE skills in PvP/Mass PvP (watch any siege video) and a pet that takes 60% of your damage + the damage it receives simply doesn't live long without Summoner-type support for the pet.
I went Soultaker on my Feoh. Yes, on people with moderate gear the debuffs are nice but all Feohs have Devil's Curse - remember that. I totally agree that the randomness of the buster debuff is what turned me off of the Elemental Nuker subtypes. It's simply not something you can depend on procing when it counts. A debuff you can cast when you want or need it. I don't like RNG.