I guess its just a matter preference.
Ill add to the above mentioned that Flex/Flock print should last longer than a regualar
DTG.
I personally prefer the Digital print, its not as thick as the Flex, feels more comfortable. Also if you are going for vintage look,
DTG is the way to go.
To me, it doesn't matter if it doesn't last as long, the tshirt itslef will look too washed after a while, so there's no point in having a print that will outlast the shirt.