May I suggest a different approach, or approaches. I have been collecting classical vinyl and CDs, since the 70's and really, it comes down so much to personal taste.I am more interested in Chamber music and late 20th century Avantgard music now, Berg Webern, Glass and Schoenberg, what my wife calls" A cacophony". So here are some suggestions
CD boxed sets: There are some marvellous box sets reissued at very low prices, by a number of Top labels, Decca, Archiv. Mercury and many others. They are very cheap and cover a wide range of music, selling for some $2 each, a steal. You can find out yourself, where your tastes lie. A good place to look is Amazon, helped by quite well informed customer review. I have a Decca and Mercury box, both are very good.
Labels to seek out: there are many which are excellent, I would put HMV and Decca at the top, but I am British. Others are Deutsch Gramaphon, Phillips, Argo, Archiv Mercury Living Presence, Reference Recordings, ECM. The latter are very good for some very obscure modern music