Preferred recordings and classical labels

I'm a fan of classical music and am somewhat overwhelmed at the variety of labels and offerings. As most of them are priced relatively similarly, can anyone offer me some general guidelines about which they prefer? Or are the performances and sonics so varied as to make it necessary to glean recommendations from those in the know? I'm interested in both CD and LP, by the way, and would like a nice balance between the perfomance itself and the recording quality.

For example, I wanted to pick up a CD of Schubert's Impromptus, op. 90, and perhaps the Moments Musicaux, but I was baffled by about a dozen different offerings. I bought the Ashkenazy recordings of the Rachmaninoff Piano Concertos on London and was happy with that, but otherwise I'm completely lost...

Can anyone help?
answer depends on how much value you place on sonics vs performance. your choice of the previn/ashkenazy pc's was excellent one for preformance and a very good one for sonics as well. every label and every performer has their successes and failures. i would suggest that rather than buy labels (performers is somewhat safer if you already enjoy one conductor for instance, or pianist, whatever) you ask for references on specific pieces of music. you can also reference the various music guides available - the only down side to that is often they only cover music in print and have little historical reference if you want to buy used lp's or cd's. you can also try AA music lane for references from other musicphiles.
I find BBC Music Magazine and Gramaphone can have insightful reviews, although I don't always trust their 'sound' judgements. Reviews are a good starting place, however. After a while you begin to get a feel for the reviewer's slant and I can usually make an intelligent decision. I agree about the Rachmanioff, especially if you want them all in a box set. Some of the better Schubert pianists, IMO, are Uchida, Goode, and Schiff and the sound of their discs are generally very good.