Kent Alarms. Family firm with straightforward approach and no sales BS. The lads who do the survey and quote are the ones who do the work.
DPA Alarms. If you have pets they can set the sensitivity so that it doesn’t pick them up. Used to have Kent Alarms but they can’t do the pet solution. Kent are good but now gone fully internet enabled if that is not an option you want.
Kent use Ajax, while it does connect to the internet so you can use your phone to enable/disable it the system will also work if the WiFi/internet fails so does not fully rely on it. It is also pet friendly so no problems if you have dogs/cats