backon has more built-in features (circuit breaker, hedging, rate limiter, generator retry, metrics, trio support, `retry_with()`), zero dependencies, and aims to be faster. tenacity is much more mature (9+ years), has a massive community (7k stars, 30M+ monthly downloads), broader Python version support (3.8+), and is battle-tested in production at scale. backon is the innovation leader; tenacity is the reliability leader.