My vote of the best episode is the one in which George does the opposite. Since all his instincts are wrong, doing the exact opposite produces astounding results.
Reasons why this is the best:
1. It's funny. It uses what we know about the character to advance the story line in surprising ways.
George: My name is George. I'm unemployed and I live with my parents. Woman: Hi, George. I'm Veronica.
2. It addresses a deep problem humorously -- overcoming fear to execise the ability to change.
George at job interview: I was fired from my previous employment for having sex with the cleaning woman on my desk.
3. It's magical. Everything works for George -- as if a divine hand is rewarding him for having courage.
George (to George Steinbrenner): I and every other citizen of
New York is sick and tired of watching you run this team into the
ground.
Steinbrenner: Hire this man.4. It has an unusually balanced, classical structure. The overall theme is: George's fortunes go up, Elaine's go down, because everything evens out for Jerry in the end.
Elaine: I'm becoming George!!!!
In short, it's both funny and inspirational. Most Seinfelds are just funny.
Veronica: Who ARE you, George Costanza?
George: I am the exact opposite of every man you have ever met.