There's no doubt about it, Sony's RX100 series has better optics but from our research, if you want pocket-ability and a long range optical zoom (more than 3-5x) you'll be hard pressed to find a better camera than the Panasonic LUMIX ZS100. It's not perfect, we wished its low light performance was better.
It weighs 11 ounces, has a 10x optical zoom, a wide-angle lens (F/2.8-5.9 aperture, 25mm-250mm), shoots 4K Ultra HD photo and video, and has a 20 megapixel sensor.
FYI, Panasonic refreshed this model with the LUMIX ZS200 (which has a 15x zoom) but the optics and speed seem to have notably suffered.
Imaging Resources has a
wonderful tool that compares the photos (of the same subject/content) being shot by different camera side by side that we highly recommend before buying a camera! The tool really helps to take the guess work and subjectivity out of most reviews.
Happy Travels!