Baskets or bags.
Some shapes of incubators work better with one or the other.
I tried tulle bags in a Brinsea Maxi, because I could not see any way to put baskets in that size/shape. It worked fairly well. The chicks did not get to stumble around the incubator playing football with the eggs, but they did not seem unhappy sitting in their bags beside their eggshells. (Very simple bags: fold a rectangle in half, sew the side and one end, put in eggs, tie a string around the open end. Open by untieing the bow or cutting it off.)
But if you like to take chicks out while other eggs are still hatching, any kind of bag or basket will be a bother because you have to open & reclose it.