Here's my prediction:
1. Carter (dude's old af and in hospice)
2. Biden (despite not having severe physical issues, mental issues can kill people pretty easily, especially with the medications they're on)
3. Clinton (looks like shit)
4. Trump (despite the poor diet, he seems to be pretty healthy and might easily be able to live into his 90s)
5. Bush (very healthy and will most likely live well into his 90s)
6. Obama (younger than everyone else, very healthy, and will most likely live well into his 90s)