Self-esteem is first and foremost between you and yourself
Never say: "I am better than so-and-so". Always put yourself in a position to confidently say: "My present self is better than my former self".
Saying: "I am better than so-and-so" is a sure sign of low self-esteem.
If you really are better than so-and-so, you don't have to say it: so-and-so will find a way to manifest it to you and announce it to the world.