Does anyone have any best practice tips or recommendations for migrating the activity history/historical engagement data from one marketing automation platform (MAP) system to another? I don't think it matters which systems, since "best practices" should be relevant across all systems, but in this case it would be a migration from Marketo to Marketing Cloud. If possible, we would prefer not to lose any historical data that we can use for reporting purposes to report on things like multi-touch attribution, conversion rates, past open/click rates, etc.
If you are planning to use this data just for reporting purpose, I would suggest moving this data to a DWH which can be further used for building dashboards.
I agree with Nadish that backing up data to a data warehouse is a good idea.
For marketing cloud, if you are moving to the b2c variant you can move existing activity data into data extensions.
No MAPs that I am aware of would let you migrate activity into the system tables for things like email sends, opens, clicks, website visits, form submissions, and so on.