Here's a side-by-side comparison - http://www.dpreview.com/products/compare/side-by-side?products=nikon_cpp600&products=panasonic_dmcfz70
I'd go with the FZ70 because it shoots RAW which produces images with a much broader dynamic range. You'll be able to recover lost details in the shadows and highlights to an extent that JPEGs simply cannot do.
On the other had, they both have very limiting exposure ranges. They both only have about 2-3 full f/stops to choose from. Neither is very good at night shots with the P600 shooting as long as 15 secs, & the FZ70 at an even more limiting 8 seconds minimum shutter speed.
A far better camera than either is the Fujifilm XQ1 at about $299.
Here's a comparison - http://www.dpreview.com/products/compare/side-by-side?products=nikon_cpp600&products=panasonic_dmcfz70&products=fujifilm_xq1
It has a sharper lens (super zooms offer a great range at the expense of lower optical quality).
It has a larger lens opening and a broader f/stop range allowing for more accurate exposures, and the ability to shoot in lower light, and to blur out backgrounds even more.
It has the same exposure control as the Nikon or Panasonic, but a much broader range of aperture and shutter speed settings. And it has the best video quality too.
As for image quality - The XQ1 has a sharper lens. It's sensor much larger. And although it has few pixels, the pixels are nearly 3x larger which provide a much larger dynamic/tonal range, and much less noise at all ISOs. Which means that while you can print as large, the prints that you do make will look clearer, cleaner and more lifelike.