Not sure if a similar poll like this has been done before, but I figured I'd start it here and see what people come up with! I had this idea while driving home in my car earlier tonight, and was wondering what I would choose myself, and found it to be pretty difficult.
On one hand, if you have a favorite band that you absolutely love, having 5 of their albums would be amazing to pick, but you might want more variety, so picking five albums from five bands, with one from each band, might prove to be more palatable in the long run. I think it just depends on how strongly you love one band and if you can stand to listen to those five albums more than five bands.
For the sake of simplicity, let's limit the albums to Studio Albums Only - no live albums, no compilations, no re-issues with bonus discs - just original studio album releases. And before anyone asks, double-albums can count as one album, as being a double is just a restriction of the format (since older doubles now fit on single CDs, it wouldn't be fair to modern doubles if they didn't count as one album - so for example, you could pick five Ayreon or five Flower Kings albums and they all be double albums - the more the merrier!).
-Marc.