I rarely have a favorite episode. I typically have favorite story arcs if anything. Though I was able to narrow it down to two episodes for Once Upon A Time last year (still not over Season 3). And I'm going to do that again for this meme... and it's from two of my favorite shows:
Probably the most fun I've had with watching episodes was the "Flarrow" episodes this season when The Flash and Arrow tv shows did a crossover. Bringing the two casts together was genius and seamless! Granted they live in the same comic universe and all so it's a lot like Disney bringing all of the Marvel comic movies together for The Avengers - meaning it all makes sense - but considering how much I love both TV shows' casts, this was just fun for two straight hours over two days.
The Flash's Season 1 Episode 8 and Arrow's Season 3 Episode 8 were just entertaining from beginning to end. Considering how dark both shows have become as their seasons have progressed, it's nice to relive the "happier" times for Team Arrow and STAR Labs. There was so much tongue in cheek within the two episodes, a ton of action, some heartfelt moments... and a lot of foreshadowing that we may not even see the result until next season for each show!
There were some fantastic moments for John Diggle (played by David Ramsey) who is my favorite character on Arrow (well, favorite one still alive/on the show). Diggle is the voice of reason, keeps the others grounded... and, well... has a GREAT reaction to the impossible.