I think that it will be a matter of aesthetics, as both the 800 and 900 series feature the same wood combination, bracing, finish, glue, etc. If you like to play in a seated position, you might appreciate the armrest featured on the 900s. I believe that the sound should be similar between the series in general. However, you may prefer the sound of one individual guitar over another. I personally prefer the 14 over the 16 for its versatility, but you'll have to decide that for yourself.
Hope this helps - enjoy your search!