Miscreated monster, dhukk (FW), Doompriest, Royal Guard and Suma Khatun I'd say. Keep that uncommon called armiger because he can be of use much later on in the game, but evreything else is a bit meh.

Kael will help you along the way but eventually will fall short

I concur with all the champions senda mentioned, but would also add golden reaper and bloodgorged to that list.

Miscreated Monster, Royal Guard, Armiger, Dhukk, Doompriest, Nethril

Soulbond  Bowyer  (Arena  Nuker,  Faction  Wars)

Doompriest  (General  Progression)  (Clan  Boss,  Arena,  Dungeons,  Faction  Wars)

Haruspex  (Faction  Wars)

Sprithost  and  Diabolist  can  be  used  in  Arena  and  faction  wars  also,  but  their  not  that  hard  to  get.  If  you  think  youre  going  to  use  them  you  can  start  farming  copies  for  books,  but  if  not  you  can  food  them  and  get  another  one  later.

Warpriest,  War  Mother,  Jizoh,  Cagebreaker,  Shaman,  Necrohunter,  and  Fang  Cleric  can  go  in  the  vault.  I  wouldnt  feed  them  them  though  because  even  though  your  bot  going  to  be  using  them  now,  you  might  need  them  later.

Delayed response from me, but just to say thanks for your input and suggestions all. Much appreciated!