It's interesting to compare the mana systems of those games:
- MtG (and Hex): Draw lands and spells intermingled, get mana flooded or screwed, game sucks.
- Shadow Era: Cards drawn are chosen strategically to be either mana or face down as lands
- Hearthstone: Mana is fixed and free
- Duelyst: Mana is fixed and free, but cards can be mullgianed once a turn midgame.
I think 2 > 4 >> 3 >>>>> 1