I would say Looker. I don't quite think Hubspot or SFDC or GA alone can support the level of full funnel visibility and analytics that you are looking for, even with the best MOPs you could hire. I have been using the Enterprise version of Looker in my past roles (6+ years) and can speak to the capability and its intuitive design for MOPS / RevOps. You do need to have an internal DA to do the data pipeline & light SQL modeling work, but they are not that difficult. Please note that I am referring to the Enterprise version not the Looker studio.