Login permissions outside of sa - SQL Server
what about:


removing them from the sa server role
give them the following server roles: dbcreator, securityadmin
give them db_owner on every user database they need
If they need to use SQL Agent, on msdb give them
SQLAgentOperatorRole
If they deploy SSIS packages, on SSISDB, give them ssis_admin


then you wait for someone's complaining and give also what they need.

Plus: 

Well, I know that this is not the best script (10 min...lol), but will solve your problem to give permissions on every database. Maybe you can improve it to solve your problem.

EXEC sp_msforeachdb @command1 = 
N'
    use ? 
    if DB_NAME() not in (''master'',''tempdb'',''model'',''msdb'',''SSISDB'') 
    CREATE USER [&lt;DOMAIN\MyGroup&gt;] FOR LOGIN [&lt;DOMAIN\MyGroup&gt;]
' 

EXEC sp_msforeachdb @command1 = 
N'
    use ? 
    if DB_NAME() not in (''master'',''tempdb'',''model'',''msdb'',''SSISDB'') 
    ALTER ROLE [db_owner] ADD MEMBER [&lt;DOMAIN\MyGroup&gt;]
'