Like edcyn said, there's something about certain recordings, call it clarity, that really grabs my attention and takes a song to a different level. To me, it sounds like you could hear a pin drop in the recording studio. These recordings share instrument separation and zero muddiness or thudding base line. A few examples:
Shine On You Crazy Diamond - Pink Floyd
Rhythm of the Rain - Dan Fogelberg
How Do I Live - LeAnn Rimes
I Can't Make You Love Me - Bonnie Raitt
Ride Like the Wind - Christopher Cross (listen to the clarity in the backing vocals by Michael McDonald)
Ribbon in the Sky - Stevie Wonder
Yes, several of these are very mellow piano based love songs which likely leads to clarity in the recordings, but the vocals are also extremely clear and unprocessed. For me, that "clarity" takes these songs to a different level and it's easy to get lost in them.