These are top and recommended Customer Attributes Extensions For Magento Ecommerce.

1) Landofcoder Customer Attributes: Magento 2 Customer Attributes Extension helps you to manage personal & business info of customer in seconds with different field types on registration form
Link: https://landofcoder.com/magento-2-customer-attributes.html/

2) Magesales Customer Attributes:
Magento 2 Customer Attributes or Custom Registration Fields will allow the admin to create custom fields for user or customers.
Link: https://www.magesales.com/magento-2-customer-attributes-registration-fields.html

3) Bsscommerce Customer Attributes
Magento 2 Customer Attributes extension allows creating new customer attributes in the Registration Form to collect additional customer information.
Link: https://bsscommerce.com/magento-2-customer-attributes-extension.html