Think you're safe with a cage? Think again...Make sure there is plenty of lighting and that there is not a "drive way" or access for a truck to reach your units.
This is partially why I stopped investing intown Atlanta...crackhead steal everything. I installed a custom metal cage set over concrete with rebar set 2' underground....crackheads came in broad daylight, hooked chains to the back of a truck parked in the yard behind, wrapped my cage and ripped the whole thing out of the ground. Cages only deter fairly honest folks!