It's so hard to choose one episode when the overall story is what stands out.
Quite fond of the first one, which no-one else seems to have mentioned yet - It does such a good job of introducing the rather large cast, setting up the whole superhero reality show concept, and getting you interested in staying to see more in everyone's individual episode. The fight with Jake (12 - 13) and the entire last arc (21 - 25) were also strong points.
So I didn't really make a choice... Sorry, they're all too good.
I loved the one where barnaby and kotetsu went to the ice rink to "relive" barnaby's childhood. It was so adorable emotion_kirakira I also liked barnany's birthday that one was hilarious. emotion_dowant
It's so hard to pick one... The final arc was SO good!!! But out of all of them, I think there's a special place in my heart for Ep. 17, because it showed just how important family was to Kotetsu. heartI cried when he apologized to Tomoe for not being able to keep his promise, and when Kaede gave him the picture she drew. (Plus the "surprise" twist, which I TOTALLY called!!)
Oddly enough I really liked episode one because the I felt the beginning was great~! Favorite episodes would have to be the SkyHigh episode with the robot girl...not sure what her name is...and episode 24~!