I guess it depends on how you look at your machine. If you are sitting and sewing on your machine the space on they right, you really don't need much space and I personally would stick with the least amount. But then if you use this space to the right for ironing and cutting, etc. while you are sewing then the larger number would be great.
If you are standing in front of your machine and looking at it, then the space on the right would be where you are sewing and the extra space is great because it holds to what you are working on.