Harsha Kumara: Personally, I'd recommend the HAI /Leviton Omni series.
They are extremely powerful and configurable units with built in telephone facility that can give voice alerts to multiple people in case of a problem, plus being voice interactive using the phone keypad for commands and having smartphone apps for monitoring and control from anywhere.
They have multiple zone inputs starting with 16 / 32 for a basic unit and expandable up to something like 170+ on the top version…
Each zone can be intruder, fire, flood, freeze or dozens of other things. When you get an alarm call, it tells you what class of alarm has been triggered – intruder, fire etc.
If you key in your code the system tells you exactly which zones/rooms have been triggered.
They can also tie in to home automation devices like X-10, UPB, Z-Wave etc. and control those or take actions based on inputs..
Just too many features and capabilities to list…
They are not cheap but the lower models (eg. Omni LTe) regularly appear on ebay as people upgrade; the same keypads & accessories work all through the range.
(Avoid the "Omni LT" if you see that on ebay – it's a much earlier version than the LTe and does not have network connection to work with the smartphone app, plus less facilities on other ways).
In general, I'd advise avoiding anything that relies on wireless sensors.
Installers like them as it makes their job simple in comparison to neatly running cables to all the sensors, but they can suffer from interference, the batteries fail eventually and the generally are less reliable and more prone to trouble than a wired system.
A fully-wired system is somewhat more work to install but gives far more peace-of-mind in the long run, which is what a security system is all about.
[Electronics designer & programmer for 40+ years].
What are you guarding against?
Having someone at home all the time, with a 10 foot wall topped by a 6ft circular pipe, with lasers ready to fire is probably the best. But it might be a little outside your budget.
A guard dog.
In what country as it varies greatly