Punk.
But, of your choices, Daniels. He's one of the best four or five wrestlers in the world and the only one who's been around TNA for a long run who hasn't won either the NWA or TNA World Heavyweight Championships.
And, just a note, technically Christian Cage didn't win the TNA World Heavyweight Championship. He only won the NWA World Heavyweight Championship (which was, at the time, under the control of the TNA booking staff). Hence Christian's 4 World Championship reigns are 2 as NWA World Heavyweight Champion and 2 as WWE World Heavyweight Champion. And, if I recall correctly (or weren't too lazy to go check my memory on Wikipedia), that's the only 4 singles World titles he's held.
wk