Very interesting, I'm currently recovering from leukimia and the only thing I thought was the fear of dying and become forgotten by everyone. Really scary if you think about it.

i'd say burning alive or drowning

burning to death, drowning, getting impaled, losing limbs, suffocation, and falling. Those are what I fear

Die while playing TB.

falling from something really high has to be the most terrifying, just falling knowing once you hit the ground, its all over. that's gotta be the most scary experience

this or anything slow with a lot of weight feet first.

hate those compacting fuckers

Drowning.
It's the ultimate test of Optimism VS Pessimism, man, do you hold your breath and hope you can save yourself, risking an even slower and agonizing departure... or do you just let it out and, for your last seconds, dwell on the doubt that maybe you could've been saved?

It also kinda plays on your survival instinct, so you won't be contemplating your life choices and shit, you'll be panicking and getting every hole filled with water.

I think the scariest would be if you are aware when you're pronounced dead by the doctors and you can hear your loved ones crying and you want to tell them but you simply cant move or talk or anything.. and you're actually aware when they're putting you in a coffin and started burying you alive and even though you tried your last ditch of effort it still didnt work and there you are laying in a dark, tight, small and suffocating wooden coffin realising the things that you should've tried to do but you were just panicking earlier that those thoughts didn't came to you, and now you starting to realise that it might be too late and all you can do is hope that something miracle would happen. I guess the most devastating part is where you were hoping for something positive to happen but it never did, but still you don't want to accept that so you kept on hoping until your last breath

i recently read about "brazen bull" and now i am scared to get into closed compact space that made of conductive material.

the scariest has to be the persians three deaths.
You get your eyes taken out, then you recover
ythen your skin gets flayed, and you get time to recover
and finally to end your suffering you get crucified.
Sounds a bit painful if you ask me