I've never made a DWR, but I use the 28 mm almost exclusively for all my cutting. I find the 45 and 60 too large to handle comfortably and the 18mm is a bit too small for most applications. I highly recommend a 28mm cutter. Now, having never made a DWR, does my opinion count? LOL
Good luck with your quilt! Trust the QB members who have made a DWR.