@imranvirk
Considering your requirement, my suggestion would be, you go for either CD100 or CG125. Both of these bikes are reliable, economical and comfortable. I have 2003 CG125, never gave me any problem ever since the purchase.
GS150 is good on comfort factor but in terms of reliability I give it 2/10. Piaggio and other Chinese stuff..stay away from them. Considering the long term effect my ultimate choice would be a CG125, a bike that I have tested and always approved of, just make sure you change the oil in time and of course keep some fuel in the tank and the bike will be running good.