What’s actually the best AI voice agent for outbound calls?

I’ve been comparing a few AI voice platforms specifically for outbound calls, and I realized I was initially looking at the wrong things. Voice quality is obviously important, but I don't think it's the deciding factor anymore. If you're actually using an AI agent for outbound calls, I'd look at: 1. Conversation handling Can it deal with interruptions, unexpected answers, objections, and people going off-script? 2. Qualification Can it understand an answer and ask the next relevant question, or is it basically just reading a decision tree? 3. Handoff If someone wants to speak with a person, can the agent transfer them while preserving the context of the conversation? 4. Actions Can it actually do something after the call, like update a CRM, book an appointment, trigger a follow-up, or qualify the lead? 5. Scale There's a big difference between handling 20 test calls and reliably handling thousands of calls. I ended up looking at Feather AI, Retell, Vapi, Bland and Synthflow. My current understanding is roughly: Platform Where I'd look at it Feather AI End-to-end business workflows Retell Custom voice applications Vapi Developer-heavy/custom builds Bland Outbound-focused calling Synthflow No-code implementations I don't think one of these is automatically the “best.” For example, someone building their own voice infrastructure might prefer Vapi or Retell, while a company trying to connect calls directly to sales or customer workflows might evaluate Feather AI differently. That's probably the bigger shift I'm seeing with these platforms. The question isn't really: “Which AI sounds the most human?” It's: “Which one can reliably complete the job I'm hiring it to do?” For anyone actually running outbound AI calls, what has mattered most in practice? Conversation quality, answer rates, qualification, integrations, or something else?