We have a situation where we have to transfer all tables from MS SQL database to another nightly. But we want to keep
the logins as it is for each server/database. The database is a bout 60 GB. What is the fastest and the most efficient way
to accompolish this task. We plan to recreate the indexes nightly as well.

You can truncate, bcp out/in (if only data)

or

or you can backup/load, but just drop the users then add your desired users after the db is loaded. You can "ALTER index all rebuild" to rebuild the idxs.