I need a new bike lock and I am chosing between a Kryptonite M18 and the Kryptonite 3000 STD.
The M18 is big and heavy and doesn't come with a mounting bracket. The 3000 is lighter and not as secure but does come with a mounting bracket.
You're more likely to get a good answer over in the commuting forum to your question.
I don't have experience of the kryptonite locks in question. However, I've always worked on the principle that the biggest, strongest lock on the market is a good deterrent (nothing is theft proof) and you should never, ever buy/use a cable lock.