If you are parking your bike somewhere regularly (home, work, etc), a ground anchor is probably the way to go. You use this to literally chain your bike to the planet!
The thieving &5$@#'s that are about nowadays, have upgraded from bolt cutters to battery powered angle grinders, so a thin chain or cable lock just isn't beefy enough.
Both are tested & approved to Sold Secure Gold.
Good luck out there people, keep 'em peeled.