question: aapt or aapt2 used for building

[MondayNitro]

it might be a dumb or even wrong question, but what does apktool use for building by default? i saw apktool has aapt, aapt64, aapt2, aapt2_64. im coming from apktool m, where it asks to use aapt or aapt2, so i couldnt help but draw parallels between the two.
also, is it possible to set default a particular tool for building?

[iBotPeaches]

aapt2 became default in Apktool 2.9.0.

You can't really set a default, but you can use --use-aapt2 and --use-aapt1 during building