AVCHD Lite or Motion JPEG?
 

The Panasonic DMC-LX5 will record HD 1280x720, in either AVCHD Lite or Motion JPEG.

Which format is preferable if it's going to be edited in FCE or iMovie, and burned to dvd or uploaded to Youtube? I'm concerned about editing problems and quality of final footage.

Haven't used your particular camera but if the bit rate is the same, frame rate is the same and all other factors are assumed equal, motion jpeg will be easier on the computer.

What kind of file types do they write to? What codecs or wrappers?

AVCHD Lite - H.264 compression). 30fps in 60P

Motion JPEG - .MOV files using Motion JPEG compression. 30fps in 60i

motion jpeg will be easier on the computer.

Thanks Sareesh.

I must mention that the bit rate is important in this case. Most likely the camera won't be recording avchd and mjpeg at the same bit rates. For better quality stick to the higher bit rate. However, if Youtube is all your're going to show it on, then it doesn't really matter, even in full HD.