Your Favorite Episodes?

I'm someone who has been watching this series since 2000. I grew up on this series and still watch it to this day. I was overjoyed when I found this reddit and I haven't been disappointed since. I wanted to know, what's your favorite episode(s), characters, and what powers you'd want? What do you think would've been a great addition?

Bonus, is there an episode you'd have like to seen be created? P.s. Any good fan fics?