I have the bfing camis from Target and like them. They allow the breast to be fully free to feed, which is important for me as I can't risk blocked ducts from constrictive bras or clothing. I just wear other shirts or tops over the camis if it isn't hot and then unbutton them or lift them over.

I have other bfing shirts with smallish openings and find they get sopping wet because the material is too close to my messy baby's mouth!