Noida investment: Biggest regret so far?

Was supposed to decide by last month but ab samajh nahi aa raha. I'm looking at Sector 157, Gold Homes Infra Pvt Ltd projects. Under-construction looks cheaper, but RERA horror stories are scaring me. Ready-to-move is expensive. Rent vs buy is a big headache, EMI is almost double the rent! My parents keep saying Noida Extension is better ROI. Honestly not sure if it’s peaked already? What's your biggest regret after investing in Noida?