I have my wizard (its actually Emillia) and im not sure which of the first two buffs is actually better just for normal training. I always see people using them, even though i still think they would only be against magical monsters, none of which are in the areas where i am training. So, obviously i don't understand just how these buffs work or just how certain elements work in the game. So, which is best: Spiritual shield, which gives Mental Resistance, or Anti-Magic shield which gives resistance against the elements. Opinions would be greatly appreciated :D

... i wouldn't rely on those buffs.I think you use orbs,1=25 vis,have fun.Might aswell Level up the earthQuake move thingy.8 enemies killed 286% increase damage of your regular attack.

wizard buffs are very useful in GE cause thats what seperates them to elementalists that are nukers, wizards has defensive buffs that you can use to make your characters stand against mobs, plus if you use it over the scouts buff then that would be great...

Anaethma-Curse(debuff).. double damage ftw..
ESP-Protection Field(buff).. good.. however you can only use 1 esp buff at a time.. and when your in protection field you cant use pots >.>
Illusionist-Sandman(debuff).. sleep
Levitation-Reverse(debuff).. this combined with birdfall.. XD
Incantation-Magic Barrier(buff) buff against magic spells
Incantation-Ignore Harm(buff) buff against debuffs
Incantation-Invulnerable(buff) buff against melee..

EDIT:
Anaethema-Stone Disease(debuff) enemy will+200 def +50 resistance but cannot move for 40sec
combined with
Tail Guard-Armor Crasher(melee offensive) reduce def to 0 for 20 seconds O.o better than curse i guess..
if used correctly.. the enemy(single target) will have 0 def and cannot move within 30-35 seconds

I'd say just learn them both. One is good against wizard and the other against elementalist. You need them both and will get them maxed eventually anyways.

But I personally don't like wizard NPCs, I think the original wizard is the most powerful of all. Full of cursing skills (PvP), got ESP, and can levitate (immue against ground melee enemies and AOE even with normal attack - max target of 3).