Home security systems. Opinions?

I'm interested in installing a home security system, but am unsure about which kind to get. I keep coming across a company called Protect America that has good prices but I see bad reviews on the Better Business Bureau website. Any opinions about this company compared to ADT, Brinks, or Life Shield? Opinions please. My girlfriend is 7 months pregnant with our first child. I'm interested in installing one soon. Thanks.