Looking for some experience from the field -
The rack I manage has two zero-U vertical PDU's supplied by the datacenter. They have fitted one on each side (one on the left, one on the right). The rack appears designed so it can also accomodate having both PDU's mounted on one side. In our case the vast majority of equipment has the PSU's on the left hand side, so at face value it would make more sense to have both PDU's on the left, enabling a short tidy cable run.
Is there a big downside to having both PDU's on one side, or is the choice pretty arbitrary?