While I think some of the guidelines offered above are helpful in making initial selections, they should not be treated as "rules." One of the best things about classical music and performances thereof is how wide open and varied are the possible choices.
Should performances try to adhere to original interpretations (however that may be divined) and be played on original instruments? I have many recordings that purport to be such "historically informed performances" and I do like some, but, I also appreciate performances that are decidedly not in that camp. For one example, I would not rule out Glenn Gould piano performances of Bach keyboard pieces just because the piano had not yet been invented. I even like some modern transcriptions, such as Bernstein's string orchestra version of Beethoven's late string quartets (No. 14 and 16, I believe).
Should performances try to adhere to original interpretations (however that may be divined) and be played on original instruments? I have many recordings that purport to be such "historically informed performances" and I do like some, but, I also appreciate performances that are decidedly not in that camp. For one example, I would not rule out Glenn Gould piano performances of Bach keyboard pieces just because the piano had not yet been invented. I even like some modern transcriptions, such as Bernstein's string orchestra version of Beethoven's late string quartets (No. 14 and 16, I believe).