Ok, these are my real thoughts on the subject.
The best way to hold a large fish is with both hands!... I'm not a big fan of the one handed gill plate hold... but it's better than holding it by the eyes.
This is not a bad vertical hold:
I am supporting part of the fishes weight with my left hand around the tail.
The best hold for a large fish IMHO is neither a vertical nor horizontal hold... but on a 45 degree angle.
I've held C&R fish both vertical and horizontal and on an angle, they have all swam away none the less for wear and tear!
I think the worst thing you can do for a fish if you plan to release it, is to have poor hook removal skills... this kills more fish than anything I know of in C&R fishing.
Thanks for all the replies and I'm glad we could keep this discussion fairly civil!