When you “duplicate” a field that is inside of a group, the new field drops to the bottom of the fields editor and not the bottom inside the group. That makes editing large forms with lots of groups way more difficult than it should be.
For the Date, DateTime and Time fields ACF lets me define both the display format and the save format. So I can display a date as “m/d/Y”, but store it as “Y-m-d” in the database. That would be nice here was well. And I can specify the format using the PHP date format instead of the JS format.
Since you can specify DISABLED and READONLY in the code, it would be nice to have checkboxes in the builder. Also, one interesting thing in ACF is that if I set a Group to READONLY, all of the fields inside of the group are affected. I don’t have to specify them individually.