Best background layer?

Hi i done some reaserch and i have see that people are using some layers (bitmap and vector) for background and i was wondering what is the best of it ?

Depending on how detailed you want your background, I would choose to do them on bitmap layers because then you have access to soft brushes, smudging and such. Painting backgrounds in Pencil though is not something I would recommend because of the lack of sortiment in brushes, but of course it comes down to your style.

As such, there is no best, drawing on vector makes it possible to scale your content to whatever size with no loss of quality. Bitmap can also scale content but because it’s pixel based, scaling with come at a loss of quality.