Noida Ext possession: My reality check

Been in real estate for years but buying my own flat in Noida Extension is a different ball game. I'm looking at Gaurs, Mahagun, and Godrej for a 3BHK around ₹1.5 Cr. Site visits pe toh sab chamakta hai, but I'm worried about the *real* construction quality after 1-2 years. Matlab, seepage issues, plaster cracks, finishing problems? I know builders play super area vs carpet area games, but what about the hidden charges at possession? PLC, maintenance deposits, OC/CC related stuff – kitna extra lagta hai? Aur builder communication during delays, do they even pick up the phone? Any specific experiences with these builders post-possession?