We are migrating from Sitecore 8.2 to 9.0.2 and decided to start with "fresh" core, web, and master databases, migrating content on top of blank databases.
What is the most efficient method to transfer role and membership data from 8.2 core database to new 9.0.2 core database? Is it possible to do with on SQL level with tool like Red Gate?
Update on 01/11/2019
All answers are helpful! We decided to proceed with option 3 in answer by @jammykam and developed custom code to move data from SQL tables (see list in accepted answer) into the new database. For that we also used solution described here to suspend and enable foreign keys in the target database.