I like David Letterman, haven't been a fan of Jay Leno, but don't regularly watch either --- once in a long while to catch an interview maybe. I used to watch more Letterman when it was edgier. Can't stand Paul the too obvious Laughing Stooge. I rather like Craig Ferguson, but just haven't been inspired to record him either. Fallon, not.
I was interested enough to TiVo (mainstream alert - using a noun as a verb!) the first Conan O'Brien show as he took over the Tonight Show.
It was hilarious! WAY WAY better than either Leno or Letterman. I laughed OUT LOUD many times. Many! And so did Terri! That's a miracle. So much so, the Catholic Church wants to take up a collection. Check it out!