If your too lazy to search, Ill put my 2 rupees in the bucket.

Benefits of Usa:
1. Your much better prepared for the USMLE
2. Easier to get a residency upon graduation
3. Less difficulty adjusting as you would have to on return from Pakistan.
4. Taken more seriously as a student/doctor initially upon graduation
5. Loans available easier
6. Better quality of education, facilities, etc.

Benefits of Pakistan
Admission much easier
Cost of tuition much cheaper
Cost of living much cheaper
Wide variety of books which are also much cheaper
Exposure to different environment
Tons of patients with diseases you would never see in usa
Hands on experience with patients
No problem regarding insurance, causing death, accidents etc