I have a Texecom Premier 48 in my house, and it's AMAZING. I can control it with an app, monitor it myselfwith SMS, and I'm sure that their wireless is great too! I can even use the X10 com to control lights. Plus, Wintex is extremely easy to use (not got the usbcom yet).
I know that Agility 3 isnt very good, but their Gardtec wired systems are OK.
Never used Enforcer or i-on but have used a BT Home Monitor before becoming an installer, which I believe is a rebadged power ax.