How could you forget the excellent Batman Beyond: Return of the Joker? Probably my favorite film out of any DC animated feature.
But this movie was on point. As a Flash showcase, it totally delivered to me more than the usual Batman/Superman fare that we get and the Wonder Woman/Green Lantern stories that were released earlier. Flash feels fast for once. It's not really a Justice League movie, despite the title, but features plenty of heroes and villians in unique roles like the fun story in Crisis on Two Earths.
The film at least felt longer than the usual 75 minute limit that was placed on previous films, which usually messes up the pacing and forces them to rush the story, which this film didn't suffer from, other than maybe not exploring Barry's alternative life as much as they could have.