I really don't hear anything great when it comes to FM sound broadcast processing here in the Philly area. The closest thing to being remotely clear is probably WRTI's HD-2 classical feed during the nighttime which is certainly a lot better than the horrible audio compression on WHYY's HD-2 stream.
For the most part, WMGK HD-2 sounds bearable, but I've been having some interesting reception problems for the past month or so. Not sure if it's the on-coming Spring weather or changes in the atmosphere, but I've getting some more dropouts than normal.
Actually, I'd almost have to say that WSTW's sound may actually be better than most of the ones out of Philly proper ever since they really boosted their signal. It's even interesting to listen to WDEL on their HD-3 stream...