This is purely my opinion so obviously you may disagree or have a different experience. In any case I wanted to relay my experience in searching for the best recorded Classical music, Now in my case this is predominately Symphonic works, Concertos and Operas. These large ensemble works have always been a challenge to record given their size, dynamics and the complexity of most orchestrations. So first let me describe what I am looking for when I listen to these types of recordings. Also I am not usually sensitive to the conductor and the actual performance so I am not including that aspect. For me sound quality is paramount and I don't care how "great" the performance I just can't listen to poor recordings. I know some of you will think that's strange and value performance over sound but not for me.  There are differences in interpretation obviously and I have listened to most of these works for over 40 years so it would have to be a pretty strange interpretation for me to nix a really good sounding recording.

Ok, so what am I looking for.

First for me is the perspective of the recording. Am I sitting in row 15 or further back or am I in the first row or worse at the podium. I want space, expansion, and atmosphere. Close up, close miked recordings for me are not what I want to hear. Close miked recordings compress the soundstage and minimize depth. It's like focusing with a telephoto lens. It feels claustrophobic. Many "Live" recording are miked this way to minimize audience noise and it's a treat to find a live recording with atmosphere and a sense of the hall.

Second is a well balanced recording where all of the instrumentalist, orchestra sections and soloists are presented just as you would hear them if you were there. In unbalanced recordings you find sections jumping out at you most likely flutes, brass and percussion. Strings in a lot of cases are miked too close and sound aggressive. When you are in the hall at a reasonable distance strings have a silken, smooth sound with no coarseness. So basically I look for a linear recording.

Third is transparency. With these scores I want to be able to hear all the sections, especially in complex parts and also in quiet parts as well. Many recordings fail at this and have a muddy midrange. Usually it's attributable to the type microphones used, or a too distant recording or the venue. And this is one of the most important aspects of Classical recording: the venue. A bad hall or studio can be a gremlin.In the old analog days almost any Decca recoding that was recorded in Kingsway Hall was wonderful. That hall is gone. I have found that the Boston Symphony recordings have always benefitted from their hall.

Fourth is overall frequency response. I mentioned linearity but the recording needs to have open and airy highs, a linear midrange and an impactful low end. Thin, bright recordings with an in your face midrange, weak low end or a depressed midrange really bother me.

So that sums up the most important characteristics I look for and here is where I find them

Telarc

This label is just amazing. What a catalog! t's hard to find a poor recording in their catalog especially anything they recorded after 1990 when they and many labels finally figured out how to record digitally. As my system has evolved and gotten better these recording did as well.The better the system the more you can appreciate these recordings. What a great engineering team. Very consistent. Only a few items in their catalog fail my list and usually for Telarc it's a venue issue.Their 16/44 recordings in many cases are equal to HiRes recordings at 24/96.Too bad they were sold and no longer record. Would have loved to hear what they could do with HiRes.

Chandos

This is also a very consistent label although since they record so many different Orchestras they do have some venue issues Chandos is thee proponent of atmospheric recordings. Very unusual to find a close miked recording with Chandos. In fact they have been consistently the most distant miked label. Now in some cases this has led to a lack of transparency. Again some of their best work is post 1990 and especially after 2000 when they started to phase in 24/96 technology. Hard to find a bad recoding in their catalog. Especially note worthy are any of their BBC Philharmonic recordings. They were sold to Naxos whose owner vows to maintain their catalog and keep producing new recordings.

Reference

What a wonderful label! Staggeringly beautiful, dynamic and life like recordings. Some of their recordings can be a little too reverberant but even then they are excellent. Unfortunately for me their new series with the Pittsburg Symphony has been a disappointment as they are live recordings miked too close for my taste but still excellent recordings.

Deutsche Gramophone

Again post 1990 they figured it out. I thought their early digital recording were too bright but when they started their 4D line it all come into place. Since the mid 90s they have been pretty consistent. In fact the Pletnev Tchaikovsky and Rachmaninoff Symphony recordings with the Russian National Orchestra are really excellent but require a good system to hear what they offer. They clearly benefit from an excellent venue. This is another series of recordings that got better as I upgraded my system. In my opinion these are the best recordings and performances of these works. DG keep getting better. Their live recordings of Shostakovich Symphonies with the Boston Symphony are exceptional. One of the best live recordings I've heard. Also their recent recordings with the Philadelphia Orchestra are excellent. And if you want to hear a really stunning recoding of Ravel's Piano Concertos DG just released a recording with Seong-Jin Cho and the Boston Symphony that is amazing in both  performance and as an example of state of the art recording.

Channel Classics

A label from the Netherlands that offers some very dynamic, well balanced  and atmospheric recordings especially their Prokofiev Symphony series.

Other labels such as BIS, Onyx, Ondine, Hyperion and Harmonia Mundi offer excellent recordings but are not as consistent. My old analog favorites Decca and EMI now part of Warner to me have not yet made the adjustment to digital. Very inconsistent and lacking transparency and soundstage compared to those mentioned above. I also include Sony/RCA in this group as well.

Ok, a long one but I would be interested in your experiences as well and let me know if you have found any labels I missed. Also would be interested in what audio qualities you value when listening to Classical music which is the most challenging type of music to record.