Burn, you sufficate before you actually burn to death. Plus drowning would be scarrier cuz you know that death would be inevitable, while with burning the pain is probably too much that you'll probably pass out and then sufficate or just sufficate.
i've read in a couple scientific articles that i did current events for school that Drowning is the number one scariest death for humans. They did simulations and shit, and they said that brain activity and people's pulses were the highest.
Burning alive has got to be the most painful expierience. At least with drowning you just expire from lack of oxygen. Plus people who have drowned have been brought back to life after 20 minutes and shit. If you live through a burn, you expierience pain constantly and are disfigued and shit. You need skin grafts and got to go to therapy. Fools have melted off nubs for hands and shit. Have you seen people who have been burnt? They fuckin melt into a whole different person. Scary as fuck.
THis is the dumbest question. It's a known fact that drowning is the most peaceful way to die.
And before you say something stupid like "Well how would you know if the people die how can they tell you?", take into consideration that people have drowned and been brought back to life before.