I agree with other posters, if you're looking at Olympus, definitely get an OM-D over the PEN 3, it is a massive improvement! But the Sony NEX-5N is incredible too.
I have the NEX-5N, it is fantastic. It has some excellent features I haven't seen on other cameras, such as the stacking for anti-blur and twilight, it also has some good effects built in such as HDR paint and vivid mode. The optional viewfinder is a must, it is awesome. I only use the Sony with manual focus lenses, like Voigtlander or Zeiss, and it works great with those. If you want to use the standard autofocus lenses, it is a bit lacking since the lens selection isn't very good yet (The Olympus has a huge selection of great lenses). The Sony is also amazing with high ISO shots, especially with handheld twilight mode.
Here's a picture I just took with it (not a watch, sorry!)
I also just picked up the OM-D (yesterday!) I had previously borrowed a PEN E-P2, and I did not warm up to it - it feels cheap, it is a bit awkward, and the high ISO shots have way too much noise. The OM-D solves all of that, it is built great (although still very light), feels very good in hand, has a great viewfinder (not as good as the Sony but theOly viewfinder is built in, and it has in body IS that is active with a half shutter press while you compose).
The in body IS on the Oly is amazing, probably the best in the business (Sony has no in body IS). From what I can see, the noise performance at high ISO is very good (much much better than the PEN, possibly rivaling the Sony although the Sony will still beat it when using handheld twilight with stacking to average out noise). The picture quality is superb and it is much easier to get sharp shots (especially with a manual lens) than the Sony, as the IS is just the best.
I haven't uploaded any pics with the OM-D (too busy at work!), but from what I can tell, it is a great camera, and I can't wait to use it more. I have a Voigtlander manual focus lens on it now so my use case will probably be different than most, but I'll use the other Olympus autofocus lenses for variety, the kit zoom should hopefully versatile for car shots and the track, where a manual focus lens is a bit of a pain to deal with! I did play around with the kit lens and although it doesn't have much of an aperture, in daylight it is very nice. Very light too (the Voigtlander is a boat anchor in weight compared to it).
Here's some more pics from the Sony, many are at high ISO where the camera excels.
Whatever you get, both are great cameras.