Some reasons I choose FreeBSD :
1. FreeBSD is a fast OS . I know you can trim the fat on a linux OS, but you have to undo some preconfigure scripted settings . You install FreeBSD, its fast . Shallow reason but still true .
2. It supports many aging machines . Unless you get into some of the older ISA type hardware, it'll run pretty solid on older machines . And, will support many of the ISA machines with the need for some occasional kernel re-compilation . This is Good, as I tend to feel the newest machines are way over rated .
3. Silly, but I like to download the entire package set from the OS I use . Just in case I need it in a pinch with no net for repo or port access . I like copying one folder and I have it all . And the folder design with links to the actual package is genius . Admittedly some Linux distros have simple repos, like Fedora .
4. The package collection is quite full . Unless you wanna use Ubuntu, or 3rd party repos in the other linux distros, its hard to find that . Not to mention FreeBSD !PORTS! .
5. FreeBSD is straight forward in probably all respects . Mind you not effortless . You will need to read . The only thing that limits the ability for many to use FreeBSD if they really wanted to, is a lack of terminology .
6. A pretty tight developement system . Also it seems that the newer implementations remove overcomplicated or reduntant steps . Like slowly killing sysinstall and birthing bsdinstall . I know some have complained about it . But, once you think about it, many of the steps that people miss from sysinstall are like a crutch and uneeded . "No...... not the comand line!!!!!" I'm not saying that the developers are not going to provide those abilities agian . But, I could appreciate them not being there . I'd rather they had less needless code to maintain, so that the could maintain the code I want to use more/most .
I have heard the phrase "The Debian Way" . I think with FreeBSD the way is "Don't make it for monkeys" .
Promote a user base that thinks when they utilise the system . I can get on-board with that .
These are some basic reasons .