I currently have Vector. They are good, fair priced. Decent reaction times to when the alarm goes off (luckily, it has only went off on our own faults.. opening doors, accidently panic buttons, etc). We also added in the fire detector. Which we have set up as well, and they call you before they send FF/EMS

Now, it is also tapped in to the automatic police call, EMS call, FF call, and 911, and we also have a fools code. (turns off alarm as if everything is normal, but lets 911 there is an emergency)
My parents have Front Point... I am going to switch to them next year when our contract runs up with Vector. Front Point is a satellite driven system. Vector is tapped into the phone lines... so, if we lose power, and phone, I have no system... If we lose phone, I have no system, even if I run a generator to keep it powered, no phone line, it's pointless... With the Front Point, I can just keep the main board powered and it's like a cell phone, I'm good to go..
Now don't get me wrong, I haven't had any issues with Vector. It is also a wireless system, except for the phone line tap. Which is the main reason, and basically only reason I am going to switch next year.
Vector:
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FrontPoint:
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