Ghaziabad resale market: Is it really a better deal?

Secondary market deals for flats in Ghaziabad are always better value than new builder projects, change my mind. My kids have moved out, so I'm selling our big house and looking for a smaller 2BHK in Madhopura ya Indirapuram. Surya Build Homes ka naya project dekha, but the super area vs carpet area math bilkul samajh nahi aa raha. Resale mein negotiation scope zyada hota hai kya? Plus, all-in cost ka kya scene hai? Ready-to-move societies mein maintenance aur hidden charges kam hote hain, sahi hai? Disagree? Tell me why.