Best shot at immortality?

What looks, at the moment, as the most feasible technology that can grant us immortality (e.g., mind uploading, cryonics)?

I posed this question to a fellow transhumanist and he argued that cryonics is the answer, but I failed to grasp his explanation. Besides, I am still struggling to learn the basics of science and transhumanism, so it would be great if you could shed some light on my question.