The OnGuard locks are ugly (sorry, just an aesthetical opinion) - and I was sort of freaked out by the five pack of keys that came with it.

I picked up a Kryptonite NY 3000 lock, the kind that comes with the flat keys but that too has similar pains with the OnGuards. I feel like I have to be so gentle with it, on top of the fact that the lock itself is super beefy. The key feels slightly flimsy and I have to hold the lock and carefully insert the key because I feel like I'm going to snap it. Sometimes (like all of you above) I have to make sure to insert it properly and get the right amount of contact/tension/alignment before it unlocks. I've found it's not uncommon to pull out the key and then try again.

However, it gives me great piece of mind.