Optimizing MQL Assignment: Leads vs. Contacts in HubSpot & Salesforce

Hi Folks, currently contemplating the right way to use the lead/contact/task object in New and existing biz. Currently, if we have the lead in our contacts, tray auto converts the lead to contact and we assign tasks on leads and contacts and assign these tasks to our reps based on routing logic. Q- Do you have a suggestion on which objects to use to handle the assignment of MQLs to both New and existing biz reps and what are the benefits of using each? We are looking at having more systems talk to each other to use automation as much as possible Current tool stack - Hubspot and tray, salesforce, gong.