Another vote for cotton duck here, but I make my own.
I do not prewash the fabric.
I cut out the basic outline of the ironing board plus a casing and seam allowance.
I sew a casing and insert elastic.
Once the cover is on and adjusted, I spritz the duck with water. (Quack!)
As it dries, the cotton duck will shrink to fit the board like a glove. The texture of the cotton duck holds my blocks as well as a Steady Betty.