Best all around / travel lens?

I have the Panasonic 14-140mm and I really enjoy (and use) it a lot. However, I have a GH2, which means the lens needs to have OIS since the camera does not have IBIS.

Since the OMD has very good IBIS, you could get the equivalent lens from Oly, and save some weight and bulk (14-150mm). The only thing is, the 14-140mm is a better lens overall in terms of sharpness, microcontrast, and overall image quality.

You certainly can use the 14-140mm on your Oly. The thing is, it is kind of a brick of a lens. It's a bit dense and hefty, and you might not enjoy it that much on the OMD due to its heft. I did try the Oly 14-150 when I was thinking about getting an OMD, but preferred the output from my 14-140mm, so I figured I'd keep and use that anyway, in spite of it being chunkier than the Oly lens. (I ended up not getting the OMD so it became a moot point after all..)

The other thing to think of is keeping your 12-50mm and adding the 40-150mm Oly lens. Now THAT is a terrific lens, and it is cheap, too. I have one of those and think the quality is superior overal to the Oly 14-150mm. However, if you want a single lens solution, my advice would be to try both the 14-140mm Panny and the 14-150mm Oly on your camera and see which one feels better in your hands. If the Panny is not too chunky for you, I would say to go with that one.

-J