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?
read Arthur Salvatores comments "AUDIO CRITIQUE" on original pressings very very enlighting.
while these sought after labels are often excellent-sounding, there's a lot of variability (not to mention the condition in which one often finds them after all these years...). as with so many things in the audio world: ignore the hype and trust your ears.
I agree that all of these are variable. IME, the "shaded dogs" in particular very widely, I have had more disappointments with them than any of the others you mention. I have rarely been disappointed by a Mercury, as long as you stay away from the Wing ones. In addition to the 6-eyes, the Columbia 2-eyes also sound quite good. There are some good labelography sites online, do a Google search and they should come up. There is a great London/Decca one for sure, and a good Mercury one as well.
Notwithstanding their variable sound quality as Musicslug indicates, the Living Stereos seem to have occupied center stage relative to the mono shaded dogs. By contrast, the monos, which can be found almost anywhere at low prices, seem to constitute the "unwanted stepchildren". Personally, I have only rarely listened to the monos, and when I did, found nothing special about their sound. Prices for the most desired Living Stereos peaked several years back, examples being Fritz Reiner's 1S/1S pressings of Rimsky-Korsakov's Scheherazade, Respighi's Pines and Fountains of Rome and Mussorgsky's Pictures At an Exhibition. Very good copies of these and other Living Stereos can be gotten at much lower prices today. Along with most all of the Mercury Living Presence stereo recordings, they generally don't command the level of respect and demand they used to. The early, big lettered black label English Deccas and the early cream and gold label English EMIs have been the "darlings" of record collectors for quite some time. I've seen Carl Schuricht's early EMI recording of Bruckner's Eighth Symphony fetch between $1200 and $1500 on a couple of occasions. The only blue label Decca reissues I'm familiar with are more readily available at very low prices. I've not noticed any significant demand for them(I have a few.)and in my opinion, their sound quality doesn't really challenge that of the earlier black labels(with both the larger and smaller lettering). Many red label Londons, which were made by Decca for the American market, typically offer very fine sound. Ditto the later issued London Stereo Treasury series(orange or reddish-orange labels only!) They are all widely available at very inexpensive prices. I strongly encourage classical lp fans to take advantage of their bargain prices. Finally, one of the reasons concerning the demand(much less, though, in contrast to the aforementioned English Deccas and EMIs)for the Columbia 6 eyes has to do with the fact that all or virtually all of them, like most of the early Deccas and EMIs, were recorded using tube equipment. Though some of these 6 eyes can sound extremely lifelike and exciting, they can also sound somewhat glarey, peaky or overly bright in some portions of the recording[s], attesting to the fact that all early stereo lps were not beyond reproach. Nevertheless, there were some extremely fine interpretations rendered by conductors like Bruno Walter, Eugene Ormandy and Leonard Bernstein. Just a final and more personal note: I find, with the passage of time, that Bernstein was a much better conductor than I had previously believed. And I say this with regard to a wide range of composers' works he recorded. I also feel his reputation will grow among the ears of quite a few others as well.