Been a while...I have started collecting again though.

Which rarity guide do you guys use that is the most accurate?
Where do they get this info from?

I have the Mike Etlier (98) and NGD(2007) one but now i see there is Rarityguide.com as well...
they seem to have different opinions on the level of rarity of some games.

For example.
NGD says 3D WorldRunner is a 1 out of 6...meaning its common.
Rarityguide.com says that same game is 43% on their rarity scale...meaning it's "sought after"