I own a house in G 14/4, as well as live there. Let me share few things from my experience;
IMO there is quite a long time to build and live in your house if you buy a plot in G 14/1,2,3 especially G 14/1.
If you want a plot of 25x40, best bet for your in first St No. 1 to St 10, which are on quite height and in the very start of G 14, giving you direct access from Service road adjoining G 13, where roads are already built. This is a very big advantage.
G 14/4 has two big issue right now, first is water supply so please make sure when you buy a plot, do double check bore is successfull in the that very street, else you will get stuck badly as foundation provide water through tanker only if you don't have bore water.2nd issue is that of streets which are broken and you need to come from G 13 side where all streets are built.
You will get good price in G 14, which is quite wide open as compared to g 13/1, the adjacent area to G 14, having lot of 24x40 plot sizes makes is more congested. In G 14/4, you will find big size plot mostly which makes it less congested which is a plus point
In the end, keeping bit lower prices, and hope to get benefit of increased margin, you will get a good bargain in G 14, which is a good option keeping in view quick access to Kashmir highway and motorway, as compared to D 12.
Hope this helps to some extent..