How to migrate databases from MS sql 2000 to MS SQL 2005/2008

There are 4 ways to migrate databases from one server to another:

1. backup bak files and restore to new server
2. copy the mdf and ldf files to new server and attached the databases to new server
   
3. use the migration wizard to move the objects and databases over
4. script the entire restore process and run in sqlcmd