The best replacement for freebsd is linux.

The best alternatives to freebsd are rated as following:
★★★★★  linux
★★★★★  openbsd
★★  windows
★★  centos
★★  netbsd
★★  debian
★★  solaris
★  freenas
★  fedora
★  pc bsd
★  ubuntu server
★  gentoo
★  linux performance
★  pcbsd
  slackware
  arch
  arch linux
  redhat
  osx
  openindiana
  linux kernel
  opensolaris
  os x
  mac os x
  suse

Your alternative for freebsd is not listed? Suggest!
Speaking about freebsd, one probably shouldn't forget about new xorg.

Other search terms related to freebsd and their ratings are:
★★★★★ new xorg
★★★ nouveau
★★★ grub
★★ kms
You have in mind a companion for freebsd and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of freebsd in all years. Click on graph for more.
freebsd
linux
openbsd