OMD vs GH3

It is far more difficult to hold than the G5 which was built with ergonomics as a prime consideration, not an artificially imposed retro look. The fact that you have to shell out extra for a reasonable grip that comes standard on the G5 and most cameras, and you don't get a built in flash tells you all you need to know about Olympus priorities.

This is fine. It looks cool, just that looks weren't one of my priorities when deciding what to buy.

The menu system is inferior to the Panasonic's, and plenty of OMD owners have who have far more knowledge than I have criticised the menus on this very forum, so it should hardly be a revelation. It is probably no more customisable than the G5, so your point's not really valid there.