My answers. Sorry, I came up late to this interesting thread.
How do you think Wings compare to other 70's bands ? As compared to Queen, ABBA, The Eagles,Fleetwood Mac or ELO? More or less in the same league, overall. Personally, I was more keen on Frank Zappa, Deep Purple, Jethro Tull, Pink Floyd, Led Zeppelin, Gentle Giant, Steely Dan, King Crimson, Emerson, Lake and Palmer and the like, back then. McCartney and Ram were good (and sometimes great), but things began to shift dangerously into insipid pop syrup with Red Rose Speedway. Band on the Run was in a class of its own, and good moments happened with parts of Venus and Mars and Back to the Egg.
Are they as good as Queen, ABBA, The Eagles ,Fleetwood Mac or ELO? In my taste, far better than ABBA; generally better than most of The Eagles, Fleetwood Mac, ELO and Queen.
Did Wings make better Singles & Albums, than the above? See above answer.
Who was best Live? Only seen ELO live, once, back then. It was OK, but far, far, way far behind the other bands stated in my first answer.
It is very hard to answer these questions because to me, music from the early 1970’s was totally different (yes, you can say much better and I would be totally OK with that) from late 1970’s pop. You can’t compare Wings with Sex Pistols or the late Zeppelin with ELO, right?
That being said, I can acknowledge that saleswise, yes, all these groups had enjoyed similar popular success.