What’s better to transfer home movies to HD or SD?

On a frame by frame scanner, the difference between SD vs. HD is obvious. On older transfer systems in some ways the SD transfer can be more desirable because in HD you simply seem to have a more obvious grain and the softer SD transfer can seem more pleasant to look at.  With a true scanner there is a bit more obvious grain as well but there is also a more obvious clarity to the image than the SD version of the same footage.  It may come down to taste on some level but we have confidence that in general HD is a better way to go.  Should you not like the HD version of your film transfer it can be easily down converted to SD.  It doesn’t work the other way around.