I like The Sheer Heart Attack cover, Jazz Isn't so bad. I think the covers Get boring during the 80's with The Works and Magic, Hot Space. Gone were the days of being creative. I do like The Miracle, Innuendo and Made In Heaven I love.
I don't think you can really call the 'A Kind Of Magic' cover boring. It may not be your cup of tea, but boring it is not, it is actually very creative. To a lesser extent this also counts for 'Hot Space'. 'The Works' indeed is quite boring, just a group photo. Same can be said about 'The Game'. (And yes, 'Flash Gordon' is boring too, but for a soundtrack it is OK and recognizable)
"The Works" is ultra-classy. "A Kind of Magic" is fun and vibrant. "Hot Space" is.. OK. Does a job in distinguishing the content from previous Queen LPs. "The Game" is a little unremarkable but embodies the feel of the LP very well, stripped back and cool (and I love the original "mirror" cover).
On topic "The Miracle" is probably the most dated cover, much like any CGI it seems amazing at the time then quickly starts to look hokey. (See also MJ's "Black and White" video, etc.)
I was listening to the latest Queen Pod show and Simon Lupton mentioned that there is talk about finally releasing The Miracle box set in 2022. Nothing official, but he wanted to let fans know. At the very least it's not forgotten by production. So that's something.