This decision will depend upon the purpose of the quilt.  Some purposes common in Australia include:
bed quilts
bed runners
placemats
table runners
wall hangings
Each of these purposes have different preferences inherent in their brief.  Most people want a bed quilt for sleeping under - a cotton batting will generally give you a cooler, lighter quilt, while a wool batting gives breath ability and warmth.

Generally a placemat and table runner need to be flat and heavily washable.
A wall hanging needs to be stable and wash ability is not going to matter as much.

Batting types readily available in Australia include:
bamboo
bamboo mixed with other material
cotton
cotton mixed with polyester
polyester
wool
wool mixed with polyester 

of course there are several brands available including
Legacy, Matilda’s own,NuWool, Prima, Sew Easy,Warm

most batting will be labelled with scrim or without scrim (scrim is a stabiliser worked in to the batting material)
some batting is available in a charcoal colour however the bulk of it is cream/white

​More reading about wadding or batting