The Moto E seems like a good set of design compromises to get the cost down. Missing a front camera is probably the biggest omission I have issue with.

The CPU is a little on the slow/weak side but I don't game
4GB of memory but comes with a micro SD slot ^
Not quite 720p display, but I am not big on retina-quality displays anyway, I just end up zooming in

Might have to buy one just to try, only if I wasn't saddled with three other recent vintage smartphones already.