Nokia Lumia 520 is a good budget phone running on windows platform.It comes with Windows Phone 8 preinstalled which can be upgradable to Windows Phone 8.1 and can also get Windows 10 when it is officially our. It comes with 512mb of RAM which is a good amount while running a Windows Phone OS.
It comes with a 5MP of rear camera by which we can take pretty decent pictures. It has only 4 inch 480x800pixels wxga display which is good in terms of clarity, different viewing angle and sunlight visibility. And yes it disappoints me because it doesn't have a front facing camera. It gets heated up as well while playing some high end games. Overe all its a good budget windows smartphone for windows lover.