What's a good upgrade from the Nokia lumia 520 that doesn't cost too much

[jkarateking]

I have a nokia lumia 520 with talk talk for £8.50 a month. I am getting a phone upgrade soon and want one that isn't too much a month. The Nokia lumia 1020 is too much a month.
I want it to have a better screen, more power and a flash on the camera.

 

[D_J]

What company do you prefer?