I just picked up a Sony NEX 6 after a rather exhaustive look into the state of the market. I care about bulk, low light performance, autofocus speed, image quality, and weight not necessarily in that order. I have a Fuji X100 and it takes absolutely stunning photos in a tiny package, but I want to take quality video and be able to switch out lenses in the backcountry. I narrowed down my comparison shopping to buying a body and a standard prime lens with a large aperture. Here were the contenders from my research:
1. Olympus OM-D EM-5 with Panasonic 20mm ƒ/1.7. It's compact, very light, and with inbody 4 stop image stabilization, it'd be a very serious low-light shooter and good for video. The camera body is weather sealed too! Unfortunately while it may be weather sealed, none of the lenses are, and the electronic viewfinder is passable but not great. Ultimately, I couldn't settle for a m4/3 sensor and the resultant image quality. $1300 for camera and lens.
2. Fuji X-E1 with Fuji 35mm ƒ/1.4. It oozes old-school style, takes the best photos of any mirrorless camera currently on the market, and the lenses are fantastic, if expensive. It also has the best low light performance of any mirrorless on the market. Unfortunately, it auto focuses slowly, it doesn't have optical image stabilization, and the video is fully automatic (non adjustable). It's also expensive. $1600 for camera and lens.
3. Sony NEX-6 with Sony 35mm ƒ/1.8 OSS. This is what I ultimately settled on. Technically, the 35mm lens isn't out until the end of December, but it's an optical image stabilized large aperture standard prime lens with super fast autofocus—it sounds almost too good to be true. Preliminary reviews have found the lens is sharp and the bokeh is pleasing. The NEX has excellent image quality, excellent video, almost equivalent low-light performance to the Fuji, and (as this article stated) focus peaking! I bought a Canon FD 50mm ƒ/1.8 for $40 today from a local camera store and mounted it to the NEX-6 with a $20 adapter. For $60, I have an excellent portrait lens that's quick enough to focus that's it not even a bother thanks to the NEX. This feature alone is worth buying into the NEX system. $1300 for camera and lens.
I hemmed and hawed for a long time, but the ability to painlessly use manual focus lenses of yesteryear make the NEX system gold. I feel like I can invest in my standard lens that will be on the camera 95% of the time, and then pick up inexpensive (but still quality) manual focus lenses for telephoto or wide angle. Wide angle lenses made for the FD mount may be slightly heavier and more bulky, but they don't fringe purple like the photos Ryan illustrated and are significantly cheaper than even the Voigtlanders (the crappiest of the M mount lenses).