I have done both. Stack and Whack you layer 6 layers of fabric in exactly the same place and fussy cut your blocks so that the stars are all different and then you can put them together in what ever way you want. One Block Wonders you layer your fabric also but you cut your pieces all the way across the width of the fabric and the six layers give you a star but you don't know how they will turn out as you go all the way across. Also when you put them together you only sew the stars into two half sections and put it together in angled strips rather than making each star independly. You have to work on a wall to see what they will look like. I think Stack and Whack would be easier to start.