so, what is the most painful way to die in the falllout universe?

I would say getting dragged by the super mutants to their lair to get tested by FEV...

Eaten while still alive by various mutated predators?

Vaporized by an energy weapon?

No comparison, the FEV experimentation that the Enclave ran on the captured Vault Dwellers from V13, there really is nothing worse than what was done to them, it literally tore them apart from the cellular level.

FEV experiments still freak me out a bit.

Well in Fallout 1 I'd say that the Vault Dweller punching The Overseer apart in one hit was by far the most gory deathscene in it.

And in Fallout New Vegas I'd say that getting to die in the sun from the heat on a cross is worst.

In Operation Anchorage I guess the worst death would be to panic about the situation, that you cannot get out of the simulation until you're reenacted a freaking war!
And if you take too long to do it then your real body is going to die back in the real world. So panicking about this and dying from taking too long in there would be pretty horrible.

In The Pitt to die by getting torn apart by an auto-axe.

In Point Lookout I guess getting to be the Hillfolk's squealing pig would be pretty horrible.

Getting killed by a wastelander... That is adding insult to injury. I'd have to say crucifiction is the worst way to go, you sit there and basically watch youself die for days. The most painful though to me is the way the survivalist from HH died. During the great war his family died, so he went to go live out his days in Zion. He saw the kids tortured and almost had a child but the mom and kid both died. Then he dies by just sitting there.

If you go before Fallout 1, I think the Great War wins.

I'd say being a failed FEV experiment.

Failed FEV is probably the most horrible death.

Being mounted on meat hooks and then chopped apart by raiders would be terrible.