Peter Gabriel to Rush Limbaugh: Stop using my music...

[Icicle]

89. Fripp is the wildcard

A large part of what made King Crimson different from other "prog" bands was Robert Fripp's use of, invention of new types of, and general innovation in, electronic signal processing. He was always messing with his electronics to see what new sounds he could get from his guitar. Genesis was not as heavy into the effects, and had a regular keyboard in Tony Banks taking up the space Fripp's otherworldly noises made in KC.
When King Crimson dropped to being pretty much a 3-piece band (Starless And Bible Black, Red, et. al.) during the John Wetton phase, Fripp definitely made up for what would have otherwise been seen as a hole in their sound.

I'd say early Genesis and King Crimson can both lay just as much clam to the "prog" mantle.
The beauty of progresssive rock is it's innovation, I see the two bands as competitors, to be sure, but as allies instead of enemies.
=)