*Technically* it is. It holds more books, has better eInk technology, has text-speech and weighs less. The K2 is comparable to the Nook, the K3 at this point in time is the better ereader. I'm not a "kindleer", I'm a reader. I'm not picky about my medium as long as it is either as book like as possible, and super user friendly.
The nook has its *objectively better* points, a touchscreen, lending capabilities, but in reality, the touchscreen is a disappointment and not a totally necessary to a "book", and considering that breaking a DRM is now legal, Kindle books are sharable as well.
I fully understand that they both have their pros and cons, however at this point in time, the K3 is the best out there. This could change next month, and if it does then I'll be right there arguing that that e-reader is the best if it is in its technology.