The only difference between using one of the available presets is not having to manually enter the incoming and outgoing mail server for the account and the account's user name when manually creating the email account on the iPhone so I'm not sure why the focus on the preset or other.
Either way the account will be set up on the iPhone but when using Other and manually entering the incoming and outgoing mail server, you can specify the server port for the outgoing mail server if needed down the road which is not possible when using the preset.
If your Yahoo Mail Plus email address includes @yahoo.com with nothing else, you should be able to use the Yahoo Preset on the iPhone.
Since you will be able to access a Yahoo Mail Plus account with the Mail application on your Mac (if you use the Mail application), after successfully creating the account with the Mail application - specifying a different server port for the SMTP server, etc., you can transfer the account settings from your Mac to the iPhone automatically via the iTunes sync process.
If not, try using the Yahoo preset on the iPhone and if this doesn't work, select Other and POP as the account type which will require manually entering the incoming and outgoing mail server, user name, etc. as when creating the email account on any email client.