I would say the NB-36H because it actually flew and because "The original crew and avionics cabin was replaced by a massive lead and rubber lined 11 ton crew section for a pilot, copilot, flight engineer and two nuclear engineers. Even the small windows had 10-12 inch thick lead glass."
The thought that the X-6[1] and WS-125[2] would be good ideas further lead me to nominate the NB-36H.
The thought that the X-6[1] and WS-125[2] would be good ideas further lead me to nominate the NB-36H.
1) https://en.wikipedia.org/wiki/Convair_X-6
2) https://en.wikipedia.org/wiki/WS-125