Just adding to this topic we use multiple layers that seems to work well
We first use MAD
I find it works well and covers all options. Plus it is being updated
Next we use
Most people whi are banned have their emails blocked requiring them to create a new one to register. These new emails are usually disposable email accounts. This app lets us block the use of people registering with disposable accounts.
Other things we do.
1. We do not delete banned or spammer accounts. Once you delete it is harder to track if it is a dupe.
2. We do IP ban, not as effective but it is another layer