Apartment as Gift Deed

Hi Sir/Mam, I seek to have legal advice from you related to the transfer of property as gift deed from Father's Sister to either me or my father. The situation has been described below in details: Currently, I own a flat in Noida district, UP which is in the name of my father's sister and registration of flat is not done yet with Noida Authority. Now, we want to transfer the allottee name from my father's sister to either on my name or my father name. We have following two options based on our limited knowledge: 1. Transfer of flat from builder before registration process begins which would cost around 1.5 lakh as transfer charges mentioned by builder. 2. Getting flat registered on my father's sister name and then transfer of flat to my father or me. However, in this case I want to confirm if the flat can be given as gift deed and exempted from tax if it can help in saving some hard earned money. Please help me in choosing the right option that would eventually help us in saving money. Regards, Vaibhav