Users should be able to select their own specific properties for deduplication

Who: Marketing Team, Support Team, Sales Team
Value: One Contact, No Duplicates, Better CRM and data management

Many CRM have customizable properties or references for the core operation of CRM - deduplication. And It's very industry-centric. For some industries, having only email as reference works, for some mobile number works better. Some may require multiple properties to be set as references. 

Solution: 

For Starters: You can give a choice of selecting deduplication criteria, keeping it limited to hubspot properties only. And then gradually including multiple properties as criteria, and expanding to custom properties.