^ Vapor Trails is a really interesting choice
Muse are a modern band I like a lot and their most progressive album is Absolution (imo).They went out of their way to make something different which always helps! It doesn't have long tracks but it has great dynamics as well as emotion laid bare and lots of atmosphere. You go on a rollercoaster ride in the best tradition of prog but its all song based with very little complexity. That doesn't matter though.Just a brilliant work.
Seventies wise I would probably stick Vangelis - Heaven and Hell well up there. That is a symphonic prog masterpeice and I don't even need to put ''imo''. It just is. Vangelis nailed it down in one album.
However I'm tempted to say the most progressive album in my collection is Aphrodites Child 666.So 'out there' that the record company waited two years to release it fearing a negative reaction.I've still not heard anything as brave and brilliant as that including King Crimson ,Genesis and anyone else for that matter.