I’m thinking the most powerful and useful mutant power for practical purposes has to be teleportation.
Having combat powers is fantastic, sure, but what good is an optic blast that can level a building? Besides the whole leveling a building thing, obviously? Clearly it would be useful if you were in the construction business, but that sort of thing is designed to fight evil mutants with equally destructive powers.
Wolverine’s claws? Same idea. Sure, maybe in the real world he’d make the ultimate gardener, but the truth is there’s no real practical purpose. Charles Xavier’s telepathic powers bring up all sorts of crazy ethical issues as our thoughts are private and should remain that way.
The ability to teleport is where it’s at. Traveling plans? Covered. Late for work? Covered. Stuck in traffic? Covered. In fact, you would have no need for any mode of transportation unless it was strictly for recreation.
Also, if your teleportation powers are strictly within the realm of line-of-sight, one can always teleport into the sky. At 100 feet in the air the horizon is 12.2 miles away. At 10000 feet? 122 miles away.
The formula is:
d(istance) = 1.22 x the square root of the h(eight) of eye.
So that means if you jump to 10,000 feet and then bamf again to the horizon again and again, you could travel 7,320 miles per minute. Or 439,200 miles per hour.
Fuck a car or a jet. I want to teleport.