Locks that work

I wouldn't use either of them as a primary lock. Ignoring the lock part, the second one (steel chain) is stronger than the cable "protected" by steel shells, which cheap bolt croppers will cut through like it was a string of liquorice. Those protected cables are a joke - bit of twisting with any bolt cutters or strong gripping tool exposes the cable within.

Both look pretty rubbish to be honest. You could snip through either of those with a pair of side cutters.

You're better off with a D lock (and try harder to not lose the keys!)

If I was really going to buy a combination lock (I would try and avoid it) I'd get this http://www.squirepadlocks.co.uk/squire-padlocks/bike-locks/bike-d-locks/hammerhead-combi-hammerhead-patented-combination-d-lock-230mm.html

A proper D-lock from a recognised company at least.

There are a few others on the site as well