I like the 12 a lot - not a lot of distortion or fall-off, and very speedy. I know that Ctein slammed it on The Online Photographer, but the lens works great for me. I don't like the 17 that much -- it has not seemed as sharp as the Panasonic 20 and the focal lengths are close enough that I don't use the 17 that much. I don't have the 14, but am tempted because the price is reasonable and the write-ups have been good.
My carry-kit is the 12/2; the 20/1.7 and the Oly 45/2, with legacy lenses for longer focal lengths. Still using the Olympus E-P2 (x2) and loving it.
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