Linux or FreeBSD

If you want to learn - then things you will learn with FreeBSD will be usable for decades. Things you will learn in Linux will last for several years at most - then they will rewrite the critical stuff again and you will have to learn other things again ... and after some time the cycle will happen again.
I like to use the example of # ifconfig to demonstrate why I recommend FreeBSD over Linux... in Linux, running which ifconfig will return stuff like /usr/bin, /usr/libexec, /sbin, or just about anything from a LONG list of possible locations, which are very distro-dependent. Not only that, the location can also change pretty much whenever a butterfly sneezes. FreeBSD offers stability in place of that.
Funny that you should pick ifconfig (perhaps you did this on purpose?) All l33t Linux d00dz know that ifconfig is old and bogus. The ip tool is the new hotness:

That is a pretty good example of what's wrong with Linux. No one ever made a name for themselves by fixing bugs in ifconfig(8). Go and write a whole new network configuration tool for Linux that becomes the standard and the job offers will beat a path to your door.
I had no idea about the Linux ip command until today... Yeah, the articles complain about how complex ifconfig is - my take is that the utility and the manpage reflect the IP model that IEEE designed around 1973 and DARPA adopted/implemented in 1978... While ip seems to reflect the OSI/RM model that first saw light in 1977.

There's some debate about whether the OSI/RM model is even useful. On one side, the 7 layers are easy to remember. On the other side, the OSI/RM model is difficult to match to existing network protocols like NFS or HTTPS... Apache can reject connections based on ip address - is that a Layer 3 or a Layer 7 action? Arguments can be made for both.