Recommendation for network monitoring systems?

To preface, networking is not my strongest suit but I am always up to learn new things and see where it takes me..

So after doing my own research I care across PRTG, and after seeing that they offer up to 100 sensors for free I decided to lab it up and play around with it. My initial thought was that it seemed relatively intuitive and not that hard to get setup and configured.

However after doing a little more research I came across multiple threads that it poses a pretty big security risk and clear text passwords are thrown out in the clear. This was a pretty big turn off because it will might eventually be used in production and we can’t have that happen obviously.

So it’s back to the drawing boards.. I figure I’d ask the community to see what’s recommended and then seeing if I can lab it up.