I personally use ADT and am happy with it. A factor in my going with the bigger name was the fact they have been around a long time and will likely be around in the future. I got my system installed by a fellow Hornfans poster who owns a company. The rep that came to my house is also a HF.com poster and they treated me very well. From my personal experience I suggest them.
If you are in Austin and want somebody from there to come by and show you what they have, pm me and I can forward their info to you.