I like the foam board because I can move it around, take to camp, put in front of shelves, walls windows.

I am using gridded flannel (with backing and bound) held by a wall mounted quilt holder. This is my portable design wall so is smaller.
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I use white flannel, too, attached to a few pieces of foam core board. I make use of my lint roller regularly to keep it from shedding stray threads.

I would just make sure you are happy with the size. I think mine is too small.

I have successfully use felt and actually have it on a rod and pulley so I can roll it up and out of the way when not in use. The felt hold my fabric in place and the rod is heavy enough that hold the the felt in place very nicely.

I have flannel on my design wall and it works great. I wrapped it around some foam core and it works well even if I want to put pins in it. I also saw a video from Eleanor Burns and she had headliner fabric on her design wall and it seemed to hold the blocks well

I am not honestly sure what is the best, but mine is flannel and it works fine. White flannel. Sometimes I go over it with a lint roller and I am not sure if you could do that with batting.