Which email providers (e.g. Gmail, Yahoo, etc) offer the most robust security for a personal email account? The recent article about Mat Honan getting hacked illustrates the challenge. The account owner is responsible for some aspects (e.g. choose a strong password, partition your information by avoiding daisy-chaining), but the service provider also has responsibilities (e.g. verify identity of people calling support, provide robust authentication).
GMail offers two-factor authentication, and Yahoo has the same feature in beta (as of August 2012). Are there other aspects to consider?
UPDATE: I accepted the answer below. The discussion has reminded me to consider the people and process involved, not just the technology.