20 years is a long time, but one LP that sticks out in my mind is Zooropa by U2. I just remember all the fuss surrounding it and I think it was overlooked mainly because most people thought of it as techno trash.
Most overlooked LPs in the last 20 years
I thought this would be a good conversation starter. Try to keep the sonic aspect out of it, just a purely musical basis would be preferred. I'm going to limit my choice to (one) right now which I'm currently listening to, The Pretenders "Last of the Independents".