how to pick first machine random out of three in shell?

I have three remote machines (machineA, machineB, machineC) from where I can copy files. If for whatever reason I can't copy from machineA, then I should copy from machineB and if for whatever reason I can't copy from machineB then start copying from machineC.

Below is the single shell command I have and I need to run it on many machines but then it means on all those machines, it will copy from machineA only.

(ssh goldy@machineA 'ls -1 /process/snap/20180418/*' | parallel -j5 'scp goldy@machineA:{} /data/files/') || (ssh goldy@machineB 'ls -1 /process/snap/20180418/*' | parallel -j5 'scp goldy@machineB:{} /data/files/') || (ssh goldy@machineC 'ls -1 /process/snap/20180418/*' | parallel -j5 'scp goldy@machineC:{} /data/files/')

Now is there any way by which I can pick first machine randomly (out of those three) instead of keeping machineA as first always. So pick first machine randomly and keep other two as the backup incase first machine is down? Is this possible to do?