If u r getting top 20 rank universities in USA thn U shud go for that leaving M tech.The reason is very simple, the basic difference between a USA study and Indian Study is the development of Vision in USA . You can more and more resources in USA as compare to India.We also have some best institue tat’s IIT even thn its not an easy task to get addmission in IIT ,so it will b far better to go for GRE.

There is very big difference between developed and developing and we are under developing nation so try for the GRE thats my suggestion

Dont consider my suggestion as the last and best try some other expert people of this field also….

have a nice time…