HBO. 90% of anything good and American has come from them.
Independants generally have seen a bit of a surge in popularity since the mid 90s whether in TV or cinema. Hollywood have been a bit freaked and with good reason - hence IMO the torrent of desperate, (in every sense of the word) ill conceived actioners in recent years.
But in answer to your question, I think TV does have better quality stuff these days - problem is, it also has more awful, trashy, lowest common denominator stuff too.