Locks that work

Hey, I'm live nearby Frankfurt, Germany. I found this thread while searching for a second lock but before I should replace my current primary lock, I guess. In about 3 oder 4 weeks I'll have to lock it every day at trade school in Frankfurt. By the way my current lock is an Abus Bordo Granit X-Plus and I read the bad review on road.cc.

I'm really not sure about which locks I should buy. My first choice was a Krypto Fahg, but I think it's too small for my old road frame.
My other choices are the Abus Extreme 59 u-lock, the Kryptonite New York M18 and Abus Granit X54.

The X54 is the cheapest, but it's secure though and a lightweight compared to the Extreme 59 and the Krypto M18. The Abus Extreme 59 is very expensive otherwise it'd already be mine. So the M18 seems to be my choice? But which second lock should I buy? Any ideas?

And I've got one question left: Why exactly is the Abus Extreme 59 more recommended than the M18?

Crypter, I don't know if you joined this thread at the end, or if you read the first page of it, as the suggested locks are there.

The Abus Granit X 59 can only be recommended above the Kryptonite M18, based on the fact that is takes 2 cuts to open it, and has a specific resistance to torsional twisting forces due to its square design. But honestly, either is excellent.