I am biased towards DEI alarms based on experience, not so much on preference.
overe th past few years i have installed many alarms (college job).. out of all the alarms that i worked with, i would say DEI makes the highest quality, least problematic alarms.
we installed more DEI alarms than anything else.. and still the other brands had more problems.
for instance, Alpine makes alarms.. they are a great Head Unit maker.. but that is where it stops.. the alarms they make are very problematic, and they offer little support to customers... every alpine alarm we ever installed didnt work quite right and many times we ended up swapping them out for a different brand... it was unfortunate because alpine remotes looked cool (thats why many people bought them)
just one example.
I install alarms off and on at my job and I would not waste my time or money on anything other then a DEI product this goes for all, you may save a buck but when you are pulling your hair out cause of simple bugs on inferor alarms that cut corners to save cost you will not be happy, All in all I have owned 11 cars throughout my life all with Viper or other Dei alarm or remote starts not one to date has had problems other then new batterys in transmitters, One last note keep in mind a product is only as good as the install its self.