Depends on what you mean by "Best". Regardless of whether or not I believe anything a caller talks about, it can still be entertaining. Like Christopher Maklin, he's completely full of shit, but he's entertaining because some of the stuff that comes out of his mouth is hilarious.
Check out Jan 31st show, with the guys from SCU, or Feb 06 with Rocky Elmore.
To be honest, the only ones I hate are when people ring up looking for life advice from mediums do astrology bullshit and so on, it rubs me the wrong way.