If you choose Barbatos you can use the Potion of Wisdom that Allan wants for a quest (permanent +5 Intelligence). Allan's quests give a little more experience, but I avoided him due to his personality.
Wesson's quests give more experience, though he requires General Raze's Cuirass armour (which I wouldn't have used, anyway). With Radcliff you can complete his quests much earlier, and have the option of giving up the second platform upgrade to get a couple extra malachite gems.
I picked Wesson, and thankfully you can use the enchanting machine directly in the battle tower, so I didn't have to hear from his wife.
Jonelath provides slightly better melee armour for the creature, while Igor is slightly better with the magic armour rating (not enough to care about, and the difference is negligible with better quality parts or on higher levels). Igor wants Stone's ring, but there is no reason to keep it yourself.
I went with Jonelath to avoid Igor's voice.
