ABS, PETG or PLA etc. If you get new branded rolls like Flashforge from amazon that come in a vacuum sealed bag do you still need to run it through a heated filament dryer for hours before use?
I have had to dry petg before. If you leave it out for ages you can hear popping when you print, it's the moisture evaporating as it hits the nozzle. Messes up the print, looks very stringy.
New filament that's been stored properly won't need drying.