I've shot them all.
They are all pretty comparable.
OCM5 is lighter.
The other weekend, I shot my well tuned LMT / AEM5 and it was considerably less gassy against a stock LMT / OCM5 which was surprising. I'm sure the OCM5 setup would edge it out though with a similar AGB / Buffer setup.
I did a video a while back comparing an Ops 12, AEM5, and OCM5