The Samsung Galaxy K Zoom is the successor to the Samsung Galaxy S4 Zoom, which was the first smartphone to feature 10x optical zoom. The Galaxy K Zoom has a 20 MP sensor, protruding lens, and a bulky body, making it more of a camera with phone functions rather than a replacement to the traditional smartphone
On one hand we have the Nokia Lumia 1020, which replaces optical zoom by adding a 40MP sensor. Even with the large sensor size, it is only capable of making up for about 3x of lossless zoom. While the 10x zoom on the Galaxy K Zoom may seem generous, the result is a bulky chassis which is hard to handle and carry around. Even though Samsung has done an amazing job making it smaller than its predecessor.
Still as a camera, the Galaxy K Zoom performs exceptionally well with features like Optical Image Stabilization (OIS) and 60fps video capture, along with its optical zoom lens. However, if you are not someone who requires optical zoom daily, the bulk of this device can become cumbersome. Especially if you are planning to use it as your daily device.
If you are looking for a cheaper deal, you could consider the less featured and even larger Galaxy S4 Zoom, which will cost you around $200 less. However those who are willing to live without optical zoom have a nice array of choices - The Sony Xperia Z2 comes with a very capable 20MP camera, while the 16MP sensor on the Samsung Galaxy S5 has also proven to be quite capable. If you want a camera with OIS, the LG G3 is a great option with its 13MP laser-guided sensors, while a budget conscious user may want to consider the more affordable LG G2 which has an almost identical camera.
If you don't mind venturing outside the Android world, the Lumia 1020 with Windows Phone is one of the best options in the market. You could also consider the Nokia Lumia 1520 or the upcoming Nokia Lumia 930 for an almost as good experience with its 20MP Carl Zeiss camera. The Nokia 808 Pureview was the company's first 40MP camera, but it lacks OIS and runs the outdated Symbian platform.
source - PhoneArena