Zendikar Resurgent
Oracle Text
Whenever you tap a land for mana, add one mana of any type that land produced. (The types of mana are white, blue, black, red, green, and colorless.)
Whenever you cast a creature spell, draw a card.
Card Rulings
1/22/2016 If the land’s mana ability produces more than one type of mana, choose one of those types to determine what mana Zendikar Resurgent produces.
1/22/2016 The last ability will resolve before the creature spell that caused it to trigger.
Solid for casual EDH
If you REALLY need another one of these effects sure, but for 7 mana I feel this isn't the best option.
Colorless as a mana type has been around since the beginning. Colorless as required payment distinct from generic is what is new, and to me it feels like a 6th color whether that was the intent or not. That used to be what made colorless special - it was never a required cost.