"Blue Lines" and "Mezzanine" are the ones to get. The former is mixture of soul, reggae and rap, very warm and happy. "Mezzanine" is a rock-electronica hybrid, much darker in tone and with a meaner sound.
"Protection" and "100th window" are basically inferior sequels, similar in style but less inspired and more generic.
I just realized that hearing Sufjan Stevens' 'Michigan' after 'Illinois' is very much the same "similar but a bit stripped down" experience as I had with 'Blue Lines'.
I just heard "Blue Lines" for the first time, and without exaggerating, I think it sounds like one of those albums that you can pick out from the 99 cent bin with your eyes closed. I'm baffled to how anyone can say that it's better than 99% of albums on the list, because I wouldn't even put it in the top 20,000.
The samples are used so poorly that it becomes kinda hilarious. The rapping & singing sound like it's straight out of a low budget movie that's about gay clubs in the U.K. I don't want to make fans mad, and still willing to give their other albums a chance, and if I'm in any way wrong, then let me know how I can appreciate this album a bit more.
I don't know, I'm definitely a fan of Blue Lines (a bit less of a fan of Mezzanine) but I think you need to place it within it's context. I mean, the album was recorded in the early nineties when urban/electronic soul was pretty much a figment of the imagination (at least as far as I know it was).
I love the haunting quality of that track- and M sounds great on it, to boot. I don't think it's in my Madonna Top 20, but I like. I won't be able to rate it in MA's catalog until I at least get the compilation. ;)