Dear Farhan:
As you have said that you are doing investment for short term, so therefore, I don't see any major jump in E-Block in short term unless possession in announced. To this effect, I would say that E-Block is very good investment but a time frame of 1 to 2 years, it would give good return in that period but not in months as it has already seen good jump in last few months. So, I agree with Nasir, if you can keep this plot for some time, it would definitely give you good return. As you are doing this for investment purposes, so you should not be worried about crushers, all these issues will be there but still the prices will increase due the fact of MPCHS reputation and development.
Phase 8 investment is also good but you should also give some time to that as prices have appreciated there a lot in the recent past. So you should not expect very huge return in weeks or months, although you may get profit depending upon your luck as price increases in Bahria Project without any prediction.
Investment in Bah Enclave project is also good one if you can give it 1 to 2.5 years time frame, that would be a brilliant project of Islamabad.
I myself have sold all plots in B-17 after getting some good return. Shifted to Bahria Enclave, Faisal Town, Multi Residencia, Ghauri Town......
Regards