Making enemies fast
Prepare for a faster Modern format!
Kaladesh is full of wonders. It is also full of Energy, which can be easily accessed by its denizens. Seems like a good fit to bring back fastlands – this time for opposing colors:
Fastlands have firmly established themselves as the third best dual lands available in Modern. In a less aggressive format the Sulfur Falls cycle would be a better fit with fetchlands, shocklands, and basic lands, but when it is of the utmost importance to use all your mana on the first three turns of the game instead of planning to cast 4-drops, fastlands become more interesting.
Besides Blackcleave Cliffs, which is 18€ after various spikes, the six years old fastlands are selling between 5 and 8 Euro now. The new lands should be cheaper than that, at least once the market is saturated.
As fastlands are worse in control decks, the lands with the more aggressive color combinations will sell better and therefore be more expensive as well.
While it is cool to have access to these new options for your mana bases, I don't expect them to slot into every deck easily. Take infect for example, where Botanical Sanctums can save you three life on the first turn in comparison to fetching a Breeding Pool, but which lands do you want to cut for the fastlands?
Burn decks might be interested in Inspiring Vantage, after all taking less damage from your own lands helps winning the damage race as well. On the other hand all versions running Wild Nacatl are probably less inspired by Vantage due to looking for actual plains and mountains to buff their cat instead.
Abzan decks will be interested in Blooming Marsh (which allows casting discard spells or Noble Hierarch on the first turn) and to a lesser extent in Concealed Courtyard, especially the new versions without Siege Rhinos. Abzan midrange was the most played deck by far at worlds (8 decks out of 24), but it wasn't very successful, winning only 45% of its matches!
Living End decks will be happy to incorporate Blooming Marsh as well, but unsurprisingly that deck performed even worse at worlds than Abzan. Why on earth would you play that deck at the world championship while Dredge is on everybody's radar?
SCG listed all five of these lands at the same starting price. Their prices will diverge soon enough, and Standard play may interfere with the prices as well, so when in doubt pick up the better ones for your Modern decks first.
Without considering personal deck preferences I would rate them in this order regarding their expected amount of play in Modern: