If you're using Clay, I'd recommend going with Lemlist or Smartlead. Lemlist is great for personalizing emails, automating outreach, and tracking responses, plus it has cool features like video personalization and dynamic variables. On the other hand, Smartlead is perfect if you're focusing on deliverability and avoiding spam filters, while also automating your outreach. Both pair really well with Clay for smooth and effective outreach campaigns. Twain and Heyreach are good, but they don’t offer as much personalization or integration, so for the best results, stick with Lemlist or Smartlead!