Best mirrorless camera?

Well, I have an Olympus E-PL2 as my less-bulky travel camera. (My Nikon D90 is my more-bulky camera.) Some of the Sony NEX camera bodies are even smaller, but their lenses are bigger. The Olympus white balance tends to be a bit reddish. With my no-longer-sold Microsoft Digital Image Pro software, subtracting that out is not too hard. Flesh tones, Caucasian and Asian seem to be pretty good with the Olympus.

http://www.martingrumet.com/coworker3.jpg

My Nikon often gives me color imbalances for which I can't get something right without something else going wrong, like the Alaska flag which should not be purple

http://www.martingrumet.com/alaska11dec11-07chena2...

The Olympus body does not do processor correction for chromatic aberration, but the 14-42mm kit lens seems to be well corrected optically. The sharpness is very good. The in-body-image-stabilization is not bad at shorter focal lengths, but it is not as useful as optical image stabilization at longer focal lengths. I have a very good tripod that fits in a small day pack, an I tend to use that more than image stabilization. The smaller Four Thirds sensor seems to have less dynamic range than the APS-C sensor of my Nikon, and I would guess that the Sony NEX would be more similar to my Nikon. If I get my exposure just right with the Olympus, it can be fine, but I have less room to brighten or darken in software later for less than perfect initial exposures. Strangely, in night scenes that require more than about 30 seconds exposure, the Olympus gets a lot of little white hot-pixel speckles, even with long exposure noise reduction turned on. The Nikon could do about 5 minutes of exposure before a hot pixel starts to show up, although they multiply a lot after that.

I always love these "I heard" things, because the source of the "I heard" is probably not even legitimate. Thing is, you can find a negative review on virtually anything on the internet, and if you listened to them all, you would never buy anything.

Always take any review or "I heard" with skepticism.

Given that, here is my opinion on your question.

While it is generally not that clear in most camera formats which brand is "best", I think the undisputed best brand of mirrorless cameras are the Sony NEX series. They are way far ahead of everyone else with the DSLR sized sensors and other features.

I think Nikon missed the boat with the smaller-sensor Nikon 1, and especially with Canon getting ready to release their APS sized sensor mirrorless camera, one wonders if Nikon has one in the works as well; which does not bode well for the Nikon 1 platform (unless of course, Nikon intends to make the Nikon the new standard for compact cameras).

However, while all of this may be true - the problem with "the best" this or that is that in 6 months, these things may no longer be true - thanks to Moores Law and the unpredictable nature of marketing.

Any differences between them will only be visible if you make a print the size of a wall and go over it with a magnifying-glass.

The Pentax K-01 gives access to a world of cheap lenses as it uses Pentax K-mount - in layman's terms it means that there are about a hundred times as many lenses that will fit it as for the other two combined - but it's an ugly brute.

It has to be your decision. Find a dealer who'll let you handle them and pick the one you like - anything else is gravy.

Minor colour bias can easily be corrected in software, and anyway may depend on a reaction between your own computer and the camera files. Always look at the files on several computers before making strong pronouncements about colour bias.

Look also at Panasonic models, which do have built-in electronic eye level viewfinders, very useful for long lenses.

Olympus PEN E-P3 or Olympus O-OMD, they are both excellent. Sony lacks in lenses, and they are not great quality.

Olympus can take Zuiko lenses (from Olympus) and also Leica lenses (from Panasonic/Lumix). I have owned both Sony and Olympus from time to time, and I can confidently say that Olympus is better in almost everything.