What's the best locking system to be used in London?

Hey all, previous owner of a stolen Honda nc750x. Fresh owner of a BMW r1200 RT.
What locking system should I use? What are your recommendations for London?

I currently own an ABUS disk lock, not sure what exact model it is, but it's more than 10 years old still works fine and a really really thick chain which doesn't fit through my wheel without scratching it. I was thinking of some kryptonite chain only, or chain + lock and keep the abus disk lock too for extra security on both wheels?

What are your thoughts? Thanks