Spellcaster/Effect
Flip: Select 1 Magic Card from your graveyard and return it to your hand.
Atk/ 300 Def/ 400
Pros
-Get 1 magic card from your graveyard
Cons
-Low attack and Defense
This card is used in almost every deck, and can be very useful. It is almost considered a staple. It can be a disadvantage when it is face up on the field because its attack is so low, and if attacked, it can do some serious damage to your life points.
Mask of Darkness
Fiend/Effect
Flip: Select 1 Trap Card from your graveyard and return it to your hand.
Atk/ 900 Def/ 400
Pros
-get 1 trap card from the graveyard
-has a higher attack than Magician of Faith
Cons
-most decks don�t have much traps
-Trap can�t be activated the same turn
This is also a good card, but since most decks don�t have much traps, it won�t be used in many cases. You also have to consider Jinzo, and the fact that there�s not always going to be a trap card in your graveyard.
Conclusion
It depends on what type of deck you have, if you have a lot of good magic cards, go with magician of Faith. If you have a lot of traps, then go with Mask of Darkness. Try not to put both of them in the same deck, but you will see magician of Faith more since Magic Cards are twice as good in most situations.