Simple rearrangeable list with a completion status per task. That seems to work for us at https://usebx.com https://usebx.com , as long as we get the granularit

Simple rearrangeable list with a completion status per task. That seems to work for us at https://usebx.com https://usebx.com , as long as we get the granularity right (i.e. each task is assigned to exactly one person).