The ButchT is the hottest in the Guinness World Records. I may be talking out of turn, but I hear that before a new species of chilli can be submitted into the Guinness Book of Records, the species/strain of chilli has to be stable. Hence, I am led to believe the Moruga has been tested as being hotter but has not been entered into the Guiness Book of Records. Totally aside from this factor, is the fact that SHU can vary vastly depending on growing conditions.
I have just done a back to back taste test of the ButchT, Douglah and Moruga as it happens (taste test videos on my blog)... and while I am no expert, I will say in my opinion that the ButchT was trumps in the heat department. The Moruga I tried did not come close. But then again the Moruga I tried may not have been grown in optimal conditions. The Douglah was in my opinion, hotter than the standard 7Pot I tried about a month or so ago. But anything over a million is insanely hot...