The line between homage and rip-off is always going to be endlessly debated. In my opinion, Stranger Things falls on the homage side of the line. The plot, atmospherics, tone, music, etc aren't really totally indebted to any one thing, but they resemble and remind us of a whole bunch of different things.
The closest actual comparison is E.T. There are lots of shots that feel like they are taken out of E.T. When I was watching it, I also noticed things taken directly from Stand By Me, Close Encounters of the Third Kind, Goonies, John Carpenter Movies, It, Flight of the Navigator, and a bevy of other films of the 1980s. That makes it closer to a Tarantino film. It wears the influences on its sleeve but creates a new story and a new feeling out of all of it.
My test for "is this a rip off or a loving rendition of its influences" is simple: does this capture the strict beat-by-beat of its influences or does it evoke what it feels like to watch its influences. Stranger things clearly falls on the latter side of that line.
Cocktail pairing: Dickel Whiskey and a carton of camel cigarettes.