patski

I have felt, held it up with 3 magnet bars from Hobby Lobby (costs $15.00) put up the felt and a piece of magnetized metal and it hold up great. Cheap too

quilttiger

Flannel is my favorite. I've used cotton batting but it gets very tired looking fast. I used flannel backing over Styrofoam/insulation board for the design wall. One design wall is not always enough so I made a folding room screen divider out of the same type of board. Then I used an old queen size flannel flat sheet. Perfect!

QuiltE

The fleece cleans up easily with a lint brush or roller.

I chose black, for two reasons.
I'd seen too many "white" design walls in LQS' that were outright grubby looking, along with all the threads, etc on them. Threads come off. Grub does not.
Plus ... an interior designer told me one time that black lets you "see" the true colours of a fabric easier than any other colour.

mighty

I used flannel, but any of the ones you mentioned would be just fine.

Plumtree

I have batting but it does have thread everywhere and I am too lazy to pick it out. I like the idea of flannel so that a tape roller would get all those fuzzies.

Nammie to 7

I used head liner fabric on mine - it was on sale so was cheaper than any other option and it works great!

AlienQuilter

Wow - all these neat ideas!