D7000 or E-M5

I know it's a big difference, at least in size, but I'm considering buying a new Nikon D7000 or an Olympus E-M5. The reason to consider both is that I have lenses for Nikon and Olympus. The ones for Nikon are all with screw drive and the ones for Olympus all require an adaptor.

For Nikon I would keep a Sigma 70-300 (no VR) and buy a 16-85For Olympus I would keep a 12-60 and a 70-300 and buy a 12-50 and maybe a 45 mm.

Any ideas about which one to choose?