Claude Sonnet is the strongest fit for triaging a message backlog because it excels at reading context, sorting messages by urgency or topic, and drafting polished replies that match your tone. You can paste batches of messages and give it a simple rubric like "label each as urgent, follow-up, or FYI, then draft a short reply" and it will work through them consistently. ChatGPT handles the same workflow well and may suit you if you already have a Plus subscription. Gemini Flash is worth considering if cost is a priority, since it is free and fast enough for high-volume triage. Claude Haiku is a lighter, lower-cost option via the API if you want to automate the process programmatically.