You don't even need good cutters to get through a cable lock. They can be defeated with tin snips, diagonal cutting pliers, or even bicycle cable/housing cutters. They deter casual theft only.

If you live somewhere where thieves are walking around with portable angle grinders, like NYC, then your only real choice is to never lock the bike outside at all. A U-lock with a hardened shackle might take about 10 minutes max with an angle grinder. The big heavy chains might take a little longer.