You are pretty much choosing six of one, half a dozen of the other. Both have solid 1/2" shackles. The biggest difference is the Kryptonite STD uses the bent foot design while the Onguard lock locks on both ends. The Onguard lock is more secure (needing two shackle cuts to remove it rather than one), but its a little bit harder to get on and off than the tried and true Bent Foot design of the Kryptonite locks. With the heel/toe design of locking, you sort of have to get a "slap" technique to make sure both pieces of the shackle are aligned then you can pull the key out, while with the bent foot design, its very easy to slip the lock on, turn the key out, and consider it done.

Besides the single versus double-point locking, its almost to the point where you can decide by price. The Onguard lock comes with five keys (and I am not sure if you can get more copies made) while the Kryptonite comes with three, and offers a way to register the key numbers where you can get more copies should you need more keys.