When we compare G-14/3 with G-15 and F-15 we should consider resale value of the house in those sectors. By Investing 5 million for 40*80 plot and add construction cost around 12 million(construction starts after 2years time) after 3 years the value of that house will be around 30 million.
But if we purchase today a plot around 4 million in G-15 or F-15 and construct a house in 10 million rupees i doubt it will cross 18-20 million in next 3 years.
So by investing now in G-14/3 i think one can gain more. Here i ignore rent gain in 2 years time by investing in G-15 because in other hand we only invest 5 million in G-14/3 but in G-15 we will invest about 14 million.
I also increase 10% construction cost/year to remain fair.