CCTV footage will assist police if there is a break in, an alarm will alert you and police something is wrong. If I were you, I would get cctv first, then an alarm, you kinda need both these days .
What do I choose, a CCTV or alarm monitoring system for my organization's security?
I would choose both. An intrusion alarm system will notify when a "point" is breached. CCTV would capture images useful in apprehending or identifying intruders. Personally I have both plus exterior automated lighting. It all depends on what you wish to protect and its value. As the saying goes, "you don't install a $300 lock on a plywood door.
Both equally important go hand in hand. If you are looking for a home security then alarm system is enough. For organization's security both is important.