Most of these aren't really Macguffins because they have an actual function other than just a race for possession. The Aether might well be a Macguffin (and a pretty cool one) because I can envision it being something that gets little or no attention in Ragnarok or the IW films.
Yeah, have to agree. Doesn't a Macguffin motivate the characters, but often get forgotten at the end of the story ? Although George Lucas describes R2 D2 as a Macguffin, as everyone's after him the film, but ultimately it's Luke's awakening to the Force that resolves the final conflict (R2 does help a bit).
I can't speak to the Agents of Shield macguffins, but the orb in GOTG definitely isn't a macguffin as it keeps the story going - sure it's a plot device but it links all the characters and ultimately ends up helping resolve the central conflict.
I guess the Aether can't be a Macguffin really, as it keeps the story rolling.
In that sense, I think it's the best. The mind stone seems to be a bit of a macguffin as it isn't vital in taking down Ultron ( I've only seen the film twice but I think they could have beaten Ultron without the Vision - although Vision does destroy the last Ultron bot).
Personally, I think it was stupid to have an infinity stone hidden in the sceptre (which the Chitauri, presumably at Thanos' direction, gave to Loki). Why would you give something like that away ?
OF course, I freely admit I could be misunderstanding the meaning of Macguffin.
I suppose a recent DC example of a Macguffin is of course the Codex in Man of Steel - it doesn't really have much to do with Superman's development, other than being a reason for Zod to come to Earth - but by the end it's brushed aside, something I didn't like (and overall I loved the film).
