We signed on with ADT specifically for the Brivo interface used with the access card system and the ability to link this interface and card system with surveillance cameras in the future. The readers constantly loose communication with the Brivo program, and each and everytime their tech claims its the internet service dropping out (all the while the same internet is working for everyone in the building just fine). This of course is after it takes up to a week and a half to get the tech there (admittedly, this last instance it "only" took 3 days) and dealing with his snarky attitude. But the icing on the cake, for us, came when we went to install the cameras. Having been assured they would work seemlessly with the Brivo interface... yeah, they have NEVER worked together. Half the time the cameras don't even work, and the user interface is extremely unfriendly for going back to view footage.
In another of our properties we have cameras provided by Ovation Networks - LOVE them. So easy to use and view footage, always working, has not lost internet connection in the over 3 years they've been installed, AND unlock ADT's, I can even access them remotely.
In this same property we elected for access cards and readers through Involta - again, LOVE them. Have had no problems and the customer service is fast and effective.