Interesting discussing and comments on iptables....
This year I write PhD thesis about OpenSource firewalls: pf, ipfw, iptables maybe some others....
I planed to cover NetBSD npf as well, but NetBSD 6 isn't released yet....
Maybe later I will translate my work and/or share my experience
Back to topic:
+ I like FreeBSD because I can build my desktop
the way I want it and
I control almost everything that is executed
+ ZFS is also nice....
+ If I install something I know where to look for files
+ I love manpages, they are great
+ No kernel updates every week
+ I like Beastie