So which is better? "GH3" or OM-D?

amtberg wrote:

The GH3 is much faster and has wireless flash, but is bulkier than the GH2.

I suspect that still image quality is a wash, while the GH3 is generally better at video. EM-5 is smaller and has IBIS. GH3 has more controls, better interface, and wifi.

Neither camera is generically better than the other. It just depends on one's needs and preferences.