The major difference is just the quests they provide your after you obtain battle tower
enchanter
The couples - more quests compare to the black smith guy, so better exp reward
Blacksmith guy - only provide 1 side quest, where others trainers will all provide 2. But you can gain 2 extra malachite gems through his quest
alchemist
barbatos - in my opinion, his reward is better in overall. You can use a stats points for yourself where the other guy allan will ask you for the potion for quest
allan - the liar, no that good in term of reward when compare to barbatos in term of quest reward. He has his so call allan brew but I doubt its that special or not
necromancer
Both are roughly the same, eventhough 1 say specialize on melee defensive and 1 on magic defensive for your creature. Even after I fully upgrade my necromancer ring, I found no increment on my creature defense figure.
skill trainer
Major difference on skill upgrade cost, which actually not important at all. I choose hermosa as I prefer a chic to be my skill trainer. I also enjoy seeing kenneth death, strike by lightning when doing some stupid pose in front of the dummy
