I cannot say enough good things about the Panasonic G3 system. True, I have not compared it against any of the other mirrorless systems, but ... I am a photographer, not an equipment reviewer.
You get 16 megapixels in a light and well-designed body. You get the option of using the eye-level viewfinder (electronic, of course) or an articulated LCD screen. The lenses are great, I believe the optics come from Leica. The focal length factor is 2x. I typically carry the 7-14, the 14-42, the 45-200, and the 100-300. I also have an optically stunning Olympus macro that I use with an adapter. So, I have full-frame equivalent of 14 to 600 mm, the longer lenses are VR, and the entire package fits in a modest-sized backpack and does not kill my weary old back. When I was trekking through jungles in Nicaragua last year, I managed to carry all this without a problem.
You can check out my website if you like (URL below). The Nicaragua portfolio photos were all taken with the G3 and the Alaska ones with the G2, the 10 MP predecessor.