TACET: classical, especially superb piano recordings
STOCKFISCH: acoustic (solo guitar and small combo, voice) also some baroque; not everyone's cup of tea, I noticed, you will either love it and think Guenter Pauler is on of the greatest producers ever (as I do) or find it over-produced and too much "in-yer-face"
First Impression Music K2HD CDs: various styles, small catalog so far
XRCD, XRCD2 and XRCD24 CDs (JVC, FIM and others): mainly for jazz
MFSL: mainly pop/rock
NAIM: careful here, you often wonder why some of the stuff ever deserved to be released (artistically, that is); anything with Antonio Forcione or Charlie Haden on it is just wonderful, though.
ECM: contemporary jazz
I'll think of a few more when I see them, may follow up then