TMassimo,

I bought that Abus Granit from Merlin Cycles in the UK and I live in the US. It's a beast; however, after watching a lot of Youtube video's, reading a lot of articles on how locks are broken and consulting other sources I have come away from U-Locks. The main reason is any of them can be broken from 15 seconds to inside 60 seconds. The key is to make your bike not an easy target. A big heavy chain with a strong lock actually, according to the multiple sources I checked takes longer to break than a U-Lock. The main thing though is to use TWO separate locks. That presents more of a delay than the bike next to yours; and, hopefully a thief will skip yours because of that.

For every day use I use this chain (I ordered a 36" chain that can go around my waist):
ABUS 12mm Maximum Security Chain - Custom Length: Lockitt.com

And this Lock with the 2" shackle and the 6-pin upgrade:
Lockitt 70 Series Steel Padlock - 6 pin cylinder: Lockitt.com

If I have to leave the bike for any length of time I take a small old Krypto U-lock and lock it with that to.