In terms of actual potency disregarding the basic land types the shock lands are probably just behind pain lands in power, in cube at least where you don't get those draws of all pain lands and end up killing yourself which can happen in constructed when running 4 copies of each pain land
Prophet of the Peak could also be a solid addition to most GU/x decks since its bigger than most everything, doesnt care whether youve found your splash color(s), and helps find what you need next
Pain and shocklands are similar in that they both cost you life to fully utilize
I'll include card name, format(s) in which the card was played, and an explanation of why the card made the list
That means you can be adding more bodies to a board with other creature tokens or give a bit more punching power to a deck that only makes noncreature tokens, like Treasures, Clues, or Food