The former will let you sacrifice any snow land you might control but costs you two mana to do so while the latter is more limited in its use of land-age but cheaper on the cost
Note that white will never be able to force the discard (except situationally) as the opponent could always choose to not pay the tax and suffer the penalty
With this in mind, Mega Aggron EX is a great option for those with a riskier play style, though it's far from a case of there being a risk of ruin
The deck adds cards like Sanguine Bond that turn your life gain into life loss for the opponent, which will bring an even quicker end to everyone else at the table
Keep in mind that each of these creatures care about any type of enchantment, except for Totem-Guide Hartebeest which can only tutor for Auras
The Psychic-type Pokmon can't attack unless the player has 4 or more of Team Rocket's Pokmon in play, but then will do over 160 damage in one attack