To me, paradox, adt or bluguard, they all have the same reliability and function. I feel theirs nothing special, because they all use the same sensors and most type of sensors work on either alarm brand. Heck they even work on those cheap china brands. Just remember to get high quality sensors so they don't fail working suddenly in 1-2 years. In the end, all do the same thing.

The only difference will be like adt where you got to pay monthly fee for their monitoring service. Most of the brands stated above have those function like sound module, home automation, gsm.... Just depends on what model you get.

So I just you check out each alarm brand and see what's the special thing they have that interest you.

Just remember its what type of sensor and the quality or brand of sensor you want to watch out.