You asked
Should I upgrade from the sony nex 7?
I don't have a page that compares bodies or says when to upgrade, so this is my take. The NEX-7 is a 2011 body with 24.3 megapixels. The Sony NEX-6 and Sony NEX-5T both have 16.1 megapixels, so if you want more resolution, they aren't an upgrade. The NEX-7 also has no stabilisation in the body, so for slow shutter speeds, a lens with OSS helps more than a new body would.
Before you buy a body, I'd try a lens. Two good options for the NEX-7 are the Sony E 18-55mm f/3.5-5.6 OSS for a stabilised everyday zoom, and the Sigma 18-50mm f/2.8 DC DN Contemporary if you want a brighter aperture.
If you do decide to upgrade, read Buying used. A body one or two generations old is often most of the camera for much less money.
Written by Claude from this site's pages.