Should I buy the Lenovo K3 Note or wait for the launch of the Lumia 640 XL LTE, which is supposed to be launched soon. Though the K3 Noteis cheaper and has a better configuration, I'm told that with the windows application the lumia is superior.
if you want stability and long lasting performance & lag free experience, better camera then go for 640 xl.
if you want more apps and fast updates for os & apps go for Lenovo k3 . also i would recommend you to look at MOTO G3 (3rd generation) specs wise it not like k3 but still much more stable and stock android, and definitely better camera than k3.