Ideally neither, but in the real world I have systems in both; any airing cupboard ones only due to them being upgrades that can't be moved or customer didn't want to pay to have them moved. I reluctantly put my parents CCTV in the loft, something I would never do for a paying customer, and the brand new UPS batteries were toast within 18 months due to the heat.
P.S You are right to secure your CCTV (at a recent raid round here they got off with £50k & kidnapping security staff as they stole the CCTV HDDs too) in your case no-one is going to steal your security equipment, nor in all reaility waste time looking for it, as for the intruder alarm you can see there are many struggling to sell at lossmaking prices...