I have a crimestopper 2 way pager remote in three of my rides.
My Elco has a basic Viper alarm (no 2 way pager). It works excellent for what I want. Then again, the Elco is parked in my garage 24/7
Car no. 5 has a Code Alarm system. Good alarm. A little pricey and I am not too happy with the fact the rubberized buttons seem to wear out with use. A big plus is the ability to add functions like pop trunk, window roll-up, acuator cycling via the auxilary channels.
Car number 6 has a Python 2 way pager remote. I like this alarm, the range and everything. I am not happy about the fact that the battery quickly drains on this remote. Have'nt figured that out just yet. It is a pain to have to resort to removing the battery from the remote, but oh well.
Overall and for the money... I'd go with the Crimestopper alarm. The three of them have proven to be very reliable systems.
Last word of caution... your alarm system will only be as good as the installation. A poor installation will give you false alarms and lots of frustration.