Hard wired systems are normally cheaper and do not require batteries to be changed as they are powered directly from the alarm system panel. Single storey properties are usually hardwired. 

If you are renting or live in a small apartment, you may want to consider a wireless alarm system. The wireless system will give you the ability to take the system with you if you decide to leave, and can be easily installed either DIY or by Dubbo Regional Alarms. 

Those that own or have purchased an existing two storey property, access to spaces between the floors may be limited and make running cables difficult and costly. A wireless system would be ideal in this situation.