The trouble with asking what is the best chain or indeed what is the best lock, is that you’ll inevitably receive a lot of replies from people who have not come close to having their bike stolen. This implies that their chain or lock must be good, which brings us round to the pound of butter in the fridge, as being equally effective.
I would just Google ‘Best motorcycle security chain’ and chose one that suits your little as possible spending limit. Quite often you’ll see chains being heavily discounted and / or including padlocks in the deal. This is on the grounds that any chain is better than no chain.
One of my chains was free, as it was dumped by thieves who had left a FireBlade in the alley behind my house, waiting to see if it had a tracker on it. Now I think about it, I should have nicked the bike…. The biter bit. The chain itself was fine, it was the cheap padlock that the thieves had mangled.
I can say that since I have had the stolen chain, my bike has not been pinched, so it must be fantastic. That and the pound of butter in the fridge, naturally.