The Daily Show is just cluttered with inside gossip about crappy news TV which I don't give a shit about either. Basically, the Daily Show has had a handful of great segments but is mostly straw-man stuff that's kinda nice, kinda meh. Colbert is fantastic but rarely really took on real issues — although his Super PAC thing was superb.
Fact is, John Oliver's show is totally amazingly great. The best of its kind, hands down (says me, someone who basically avoids TV shows and actually has only a modest sense of what's out there).