The drop-down literally has "It is better that," and all those words were given as choices, but it was marked wrong when I put that. It should accept both answers.
Can this both mean ''it is better'' and ''it is best''?
No. Bora would mean best. If you wanted to say 'the best' that would be 'bora kabisa'
"Preferably" is also acceptable. DL needs to do more homework.