If you look at the level of technology involved, Clifford alarms are considerably better than most others in the market place - All of their competitors are generally one generation of development behind. Clifford are the biggest/best for this very reason. Clifford are genuine innnovators in their field.
As an example, as far as I know, no other manufacture offers wireless modules, for untraceable/un-hackable installations, and this was their last generation stuff. There is a lot of hype that surrounds clifford stuff, and it is for good reason. Do all alarm manufacturers offer a lifetime warranty?
I wouldn't consider anything else for my own car, but as we all always say, each to their own, you pays your money, you takes your choice.