Do you think is the SNMP best protocol to use to manage the network?

yes I thinks so, because SNMP is a simple protocol, it largely retains the advantage and therefore is a good solution for the management of computer networks.
However, weaknesses in the protocol security.
In its latest version, the weaknesses are improved.
But with their known benefits, SNMP is the best solution to manage a computer network.
This is the reason why most computer networks today use.

Netflow is also out there but it is resource intensive. However if your network capacity allows you, it is also best. Various network management tools in the market however depend on SNMP though.

 

Ramzi, can you please tell me how can you use routing protocols (eg EIGRP, OSPF, BGP) as monitoring protocols? This is totally wrong. 

Monitoring protocols are SNMP, WMI, NetFlow etc... You're making a very big confusion in here.

Now to answer your question:

SNMP uses a single port - UDP161, whereas WMI uses a wide range of ports. Thus, for monitoring Windows OSs in a local network, inside your firewalls, I'd recommend WMI, it offers a lot more information without needing to use special OIDs to get SNMP data. If you want to monitor networks that are comprised of multiple locations, thus you have firewalls between your pollers and the monitored objects, use SNMP, cause it reduces the possible attack surface to your network.

Also, SNMP v3 offers encryption for the monitored data, and anyone who uses a packet sniffer will need your securables in order to decrypt the information.