What better way ? Create own event or use afterSave/beforeSave methods?

Question

I need to handle event changing Base currency (admin panel). But magento 2 doesn't have one. So i have two options to solve this.

• Create own event and observer for

• Create plugin for afterSave method

  <type name="Magento\Config\Model\Config\Backend\Currency\Base">
                  <plugin name="namespace_config_currency_plugin"
                  type="Namespace\Config\Model\Config\Backend\Currency\Plugin"
                  sortOrder="10"
                  disabled="false"/>
  </type>
  

I wonder which way is more appropriate or less expensive for system. Thanks!