Sector 24 builders are promising too much – unrealistic?

Visited a bunch of projects in Sector 24 last week. I'm looking for at least a 3BHK, good for the kids, close to a decent school, you know? My wife's priority is safety. But honestly, some of the builders are making wild claims about appreciation in the next few years. Like, 20% ROI? Seriously? Is anyone actually seeing that kind of return? I'm also hearing stories about delayed possessions. Anyone else facing that issue here? Also, what's the real deal with the maintenance charges after OC? Are they worth it, or are we getting ripped off? Should I consider resale instead? What are your experiences? Need some real talk.