Rebuild or Reorganize index
First question - are you using SSD or hard disks. If you are using SSD you probably don't need to do index maintenance at all (maybe once or twice a year) as doing a random read has no cost disadvantage over doing a sequential read.
That said if your database is not in use a rebuild ought to be perfectly fine, be aware that the transaction log should be sized to be equal in size to the largest table as the rebuild will be done in a single transaction.