Benefits of Using Email Sending Tools Over HubSpot for Non-Profits

Hey Clay users, a question about email sending tools. We are a small non-profit, so very limited in budgets and resources. We are very happy to adopt Clay and now we add leads to Hubspot and send sequences from there. Question: It seems like most of you use additional tool for sequences like Lemlist or Instantly, what exactly are the biggest benefits over staying in Hubspot? Thanks!