I am a fan of Windows Mobile especially the Lumia Phones. My current phone is a Nokia Lumia 1520 which I have been using since October 2013. A very strong phone for power users, excellent battery back up and very stable. I have been waiting for the next upgrade for some time now, but will have to wait till we have the Windows 10 mobile is released. As per reports, there will be no Lumia Flagship devices until Windows 10 Mobile is released and recent rumors tell that the next flagship device would be Lumia 940 and Lumia 940 XL.
Lumia 940 will have 3GB Ram, 25MP Camera and many other new features like Iris sensors, 5.2 inch display, which the Lumia 940XL would have 5.7 inch display. These are all rumors but from reliable sources of the industry.
We need to wait for the BUILD conference which is on the 29th of April 2015 for more information on Lumia Flagship devices and other upcoming devices. We may also get some information on the release of Windows 10.