Well, depends on what kind of bussiness they're running.
a ) For small companies:
If they deal mostly with excel (office) based stuff, sadly linux is not a viable option and won't ever be. M$ office in the current state outshines every other option, by miles, mostly because people force VBA down your throat.. and libreoffice/openoffice aren't even worth the effort, like really.
Kali if you deal with security, it's so complete and pretty easy to use. Parrot is a good sidekick for it.
Arch if it's experienced people used to linux. It's pretty much the "one ring to rule them all" distro. With little research you can find out why. Manjaro also does the deal, adding some extra packages that might not be wanted.
Deepin is ultra good if it deals with education and/or new people using the computers, as it's very grandma friendly.
Debian/Cent are good if you need a reliable server.. Arch is fucking awesome as well. All of those are free.
I personally dislike most of new Debian-based distros though, as it gives the feel that it's being over-stacked with useless packages that add ease-of-use, at the cost of being a fat resource hog.
b ) For big companies ($$$$): SUSE (opensuse leap is probably #1 atm), Red Hat Enterprise plus fedora for smaller stations and off-the-company usage.
c ) For extreme big dick companies (the overall king, the supreme, the master, the untouchable): SOLARIS! (it's 100% unix though)
This post was edited by jacob1818 on Feb 10 2017 10:48pm