it all depends on how far the car is taken apart and how much money u have. and how much trouble u want to go to ....
and if u know what is under the paint u coulf find a heap of old repairs and they will need to be done again
if the car is a bare shell i would use none of them i would get it chemically dipped .
sand blasting is all right but get it done by a pro back yard people could do damage to your panels.
if u are gonna strip it get your hands on some aircraft stripper it'll take it all off including body fillers..
blocking will just take way to long