I've voted for Hot Space. Nobody rates it, which is probably why I like it. I like the fact Queen moved away from the more standard rockier stuff and dabbled with disco and funk. There's also a song where Freddie sings falsetto all the way through, much like Jimmy Somerville would just a couple of years later.
I also like Innuendo and even Made in Heaven.
I've yet to hear A Kind of Magic and The Miracle; The Works is okay. I've heard bits and pieces of their early albums but prefer just having the Greatest Hits which covers those.
Like with Elton John, I pick up with Queen where my dad leaves off, so basically late 70s/early 80s. He actually recently gave me all of their 80s albums + Innuendo on CD which he never listened to.