Before you get one of those, what will you be using the lock for? They are not a real deterrant if your ride is nice meaning if you're gonna leave your bike out all day. With 2 people and a van. Gone in 10 seconds.
I've used a Xena. It can be annoying how it goes off on it's own sometimes. The pin size you choose depends on how you want to mount it (bigger is better but they can all be taken off pretty easily). Smaller sizes (~6mm) would allow you to put it through the drilled holes in the brake disk.