Contact reporting is used for your communications reporting: emails, direct mailers and mail merges.
Your Flipcause Contact Database allows you to manage your contacts, households, groups, etc. and keep them updated. For this reason, your Contact Reports is where the contact information will be the most accurate and up-to-date. In contrast, your activity and transactions reports will only pull the information exactly as it was entered at the time of the transaction, leaving you stuck with potentially outdated emails or addresses, or ones that contain typos.
We recommend pulling Contact reports for emailing, so that each person gets their own email.
For something like direct mailers, we recommend pulling Group reports, to avoid sending multiple duplicate flyers to the same house.