Sold Secure rates the best locks as "Gold", the second best as "Silver", and the lowest approved level is "bronze". You can get the weights for each lock at the company websites for Kryptonite, Abus, and OnGuard.

The "lightest" lock on the "Gold" list is the Kryptonite New York lock, at four pounds. Many of the other "Gold" level locks weigh five, six, eight, and even ten pounds. Yikes.

That Magnum UL1 that earned a "Gold" is the much cheaper brother of the OnGuard Brute. It is probably the cheapest lock on the "Gold" list, but seems hard to find outside of the United Kingdom.