CLassical: Rca, London, Col, Mercury.....

Rca "shaded dog" LCS-Living stereo releases are highly coveted buy what about the mono(LM) shaded dogs? Are they desireable as well?l Also, what is the difference between blue label and red label London-Deccca releases? Most prefer the blue. In the same train of thought, why are Columbia 6 eye releases so coveted as well? Are the Mercury Living Presence series all that and a bag of chips?