Here's a $0.50 card that is already buylisting for almost its retail price. While each of the 3 effects that you can choose from typically cost less than 4 mana, it's the pure versatility of this card that in many players' eyes makes this card worth playing. Redirect and Twincast are typically 2-mana effects, and Cancel is 3 mana. But having these choices in a control deck could be quite relevant. It's already seeing a good amount of play in Commander. If this sees any play in any Top 8 deck in Kaladesh Standard, this could easily surpass its pre-order price of $2.
When Gatecrash was first released, Blind Obedience looked like it was going to be the answer to aggro. While it wasn't, it was a pretty good card. This Enchantment doesn't tap down artifacts, but it's only a one-drop. There's also another major difference with Authority over Obedience, and that is gaining 1 life for each creature that enters the battlefield under an opponent's control. This seems like it would be a solid sideboard card, and incremental lifegain does make a difference against creature-based decks. This is an Enchantment that I could see sneaking into Modern and perhaps even Legacy.
Dwarves are definitely pushed in Kaladesh to serve as the core of a Vehicles deck. In the early going, this has proven to be true. Depala, even being Legendary, is good as a three-of to pump both other Dwarves and Vehicles by +1/+1. But the power and toughness boost isn't even the bets part about Depala. Being able to draw multiple cards is pretty good, too. That X ability can't be understated. Plus, it's not an attack trigger; it's whenever she becomes tapped. This means that when she Crews a vehicle, you get to use that ability. With Veteran Motorist's Scry ability, you will often know what the top card or two of your library is, making her ability often a draw 1 or draw 2 for only a couple of mana. She's really solid.
Speaking of Dwarves...
This Dwarf looks like it could be pretty exceptional. Already he's seeing play in Boros Dwarves and turning him into a 2/3 is extremely easy. Thraben Inspector brings along a Clue token that gives yiu the artifact, as well as Pia Nalaar. Smuggler's Copter, Fleetwood Cruiser, and Skysoverign, Consul Flagship are all solid vehicles to serve as other artifacts in the deck. A 2/3 who will often have first strike for only one mana is super good, and Depala, Pilot Exemplar pumps him into a 3/4. It's possible we'll see him in other formats, as well where artifacts are far more plentiful.
This artifact is a deck brewer's dream. Already, Panharmonicon is seeing play in a variety of Commander decks. But at only 4 mana, this is definitely a Constructed playable artifact. Abe Sargent came up with 10 great ways to abuse Panharmonicon in Kitchen Table Magic. Since it has so much casual appear, this card will easily maintain an above-bulk price. Will it break into competitive play? There are so many triggered abilities in Magic, and in many ways, this is better than Strionic Resonator, a very popular Kitchen Table card. There's no activation cost and it's only a matter of time before someone breaks it in some format, whether it be Standard (post Aether Revolt), Modern, or Legacy.
Kaladesh looks to be a really solid set. While prices will be kept down by the Kaladesh Inventions, there is a ton of playable stuff to collect in this set. When we revisit Kaladesh after some time has passed, we'll see if any of these five break out. In any case, these five picks feel fairly safe.