Picking lenses for mft can be tough if you don't own any already.
I have nikon lenses and mft lenses for my gh3, I only have nikon because thats what I already had, but you also don't need an electronic adapter for nikon lenses, which is nice.
As for mft lenses, there are plenty of great lenses, they are just a bit more expensive. The rokinon 7.5mm fish is a great lens if you want a fisheye, the olympus 12-40 is an amazing lens, but its $900. Panasonic makes a wide variety of lenses, you'll get what you pay for but they're all pretty decent.
I use a tokina 11-16 and tamron 17-50 with my kit, both work very well, but you'll need to choose nikon or canon. I also have a rokinon 8mm, panasonic 20mm and a nikon 70-210 (old lens).
TBH you best bet is probably the panasonic 14-42 kit along with a 45-150 would be a good start, but if you have like $2000 to spend on lenses, you can ball out with some olympus stuff, or go nikon/canon with an adapter.