Id say this one:
http://3.bp.blogspot.com/-xWJsldAuEjg/T7mib1T6cII/AAAAAAAADWU/egS0c9uBRZw/s1600/monstersandmen.jpg
but its been gaining ground locally after they played Little Talks on the radio (though to be fair I only heard it cause a friend works in radio and she let me hear it early to see what I thought, so its not like im complaining or getting hipster). Which isnt to say I dont like the band or album anymore, just I cant say not a lot of people have heard of it (though I still think a large majority of people who do know who they are in my area only really know little talks or Mountain sounds maybe).
Now this one:
http://images.cryhavok.org/d/5226-1/Demons+_amp_+Wizards+-+Touhced+by+the+Crimson+King.jpg
Always seems to get a reliable "I dont know that one" or depending on the age, "Thats not a band, thats an album by Uriah Heep," whcih then usually devolves into muttering or arguing that people my age (young twenties) dont know any good music.
However, some people do know it from being metal fans, while others know it from the dark tower series its associated with (how I found out), and others know it cause of both.