hey here is my opinion:
fire: is best for both ATK and MATK because it got gs and fire is used for hard quest
water: is best for support because water has the speels and revive but they can be good mages too but not better than fire ones
earth:best for tanks and knights because they ussualy have HUGE con and they stand the last in fierce battles
wind:the best killers you will saw are the wind ones even that die easy in front of a fire char they got HUGE spd and they are great for battles when you need to be fast this is what i think if you need help choosing the best char for the element you chose pls tell me :)

<---pls click to make them grow,i click yours :)