I don't think his voice was better than on Bad tour...
Is not that his vocals were better or less better on the Bad Tour is that at that time Michael was not having all the problems he was having with his body, so will sing live the entire concerts, the vocals on the Bad tour are excellent so in the Dangerous tour and also in the History tour, the difference is that he had developed a much unique style of singing, over the years he would design the way he wanted to sing, he was a perfectionist, and on the History tour i mean he did not lip-sync all songs, some of them were entirely sung live, there were songs that he at some tours would sing live and at other tours he woud lip sync but not entirely, the firsts parts he would do it but he always at the middle or the end of songs would sing live, this that im going to say is imporrtant for it may be areason why lip-sync some songs at some times, Michael came to Argentina in 1993 and when he died a man named Hector Caballero who was the one who bring him here to perform spoke of how
Michael was injected with morphine before the shows started, the reason for it to be inh¡jected was the Michael suffered body pain, real bad, so the only way he could make them desappaer was with morphine, but still at that time 1993 he would sing live most songs, i guess in the History tour the pain was much greater, i cant blame him, i dont know why he had all that pain, some says he had a bad back problem, some other say he had problems on his foot or his knees, but the man Hector Caballero said it was amazing to see how michael out of stage was like a kid, kinda shy and naive, but whene he put his feet onstage he would convert into this God of music and dance, he said it was amazing to see.
However, his vocals on albums were 10 times better on Dangerous.
I have to agree on that, i love his voice on the Dangerous album, but the way he sings in Smooth Criminal, Speed Demon from the Bad album, were AMAZING, it was the beggining of the way he started to sing from Dangerous to his last album, his voice was more calm in the Invincible album however on songs like Invincible or Heartbreaker well he was very angry i guess hahah