Security

[Alex321]

Forget about cable-locks, they can be cut with a pair of wire-cutters. Get a D-lock that's at least silver rated, they provide the best balance between security and price. Gold rated locks only stand attack for 2 minutes longer but usually cost a lot more.
https://www.evanscycles.com/brand/lifeline/d-lock---sold-secure-silver-930033

I wouldn't just say "forget about cable locks".

There are a couple that are sold secure Gold rated and a few that are silver rated. They certainly can't all be cut with a regular pair of wire cutters, though proper bolt cutters will get through most.