Without a doubt use Docker. It has the ecosystem, which is extremely important. It also has the support and community.
For devops engineers looking to build an entire enterprise around containers, LXD will be a great option when it reaches maturity and its ecosystem matures. It's not there yet, and probably won't be for a few years.
Another great company that's doing extremely cool things with LXC minus Docker is Flockport[0]
So flockport is a competitor to Docker? Seems to do what Docker does. So many choices. CoreOS too . Docker has the momentum and VC$. Hard to really know what the "right" choice is.
For devops engineers looking to build an entire enterprise around containers, LXD will be a great option when it reaches maturity and its ecosystem matures. It's not there yet, and probably won't be for a few years.
Another great company that's doing extremely cool things with LXC minus Docker is Flockport[0]
[0] http://www.flockport.com/