Many fans were devastated by the news that One Piece was on a hiatus due to Toei animation being hacked (via ComicBook.com). However, there was a silver lining as the creators promised that the next few episodes of the anime would have better pacing and animation.
While this means that some filler episodes will be cut, the show will not get rid of them altogether as there are many viewers who love to watch them too (as they provide a nice break from the intense drama). The Dragon Ball franchise is a perfect example of how they could implement this correctly as the creators of that show managed to find a perfect balance between action and drama, and the light-hearted fun.
DB Episode 81 - Goku Goes to Demon Land
Many of Goku's trials prior to the 23rd Tournament were interesting and each of them blurred in some unique Chinese or Japanese folklore. Goku's trip in this episode involves meeting a king and queen and then saving the daughter from a man who wants to marry her. It comes off as a very typical romantic knight tale, except here it's cheerful Goku as 'the hero.'
Goku enters what is known as Demon Land and faces off against, obviously, demons. There he faces Shura, who Goku is surprisingly weaker than. He does succeed but uses the light of the Kamehameha to defeat him. What's so fun about this episode is that the Demon Land or Demon Realm actually appears again in canon. It's also a fun episode to watch for those who have seen The Sleeping Princess in Devil's Castle movie as there are many references from the film here.
DBZ Episode 14 - Princess Snake
Most filler episodes tend to lean toward the humorous side and the "Princess Snake" is one of those. Here, Goku falls into a food trap as Princess Snake slowly falls for Goku, but decides she'll just eat him after learning about his love for his family.
The episode features many surprising moments of comedy, such as the Goku eating everyone's dinners, but also heartfelt moments that remind Goku why he's here on Snakeway and to continue on his journey. Goku escaping Princess Snake's belly is also very memorable as he soon tangles her into a knot.
DBZ Episode 13 - Goz and Mez
Goku goes to Hell, otherwise called "HFIL" (Home for infinite losers). Goku's twisting endeavors against the two ogres are fun and, like all of the Snakeway episodes, bring more details on King Yemma. Against Goz, Goku displays his abnormal strength. But while against Mez, Goku also showcases his phenomenal speed.
This episode was certainly made to just pass time, but the details seen in Hell are interesting and surprisingly fun, with the torturous mountain hikes and the souls rowing in a boat in the Blood Pond. It's also interesting to see a forbidden fruit from a tree not meant for anyone but King Yemma, much similar to the Forbidden Fruit in the Bible (although Goku does grab one because he's hungry).
DBZ Episode 17 - Pendulum Room Peril
This episode is a reused idea of an episode from Dragon Ball called the "Time Room." This time, it is Yamcha, Tien, Krillin, and Chiaotzu who travel to the past and face off against two Saiyan warriors. There are several episodes where Toei tries to craft their ideas of what the Saiyans would have been like in the past and this is one of those.
The ruins surrounding the characters have a mix of barbarian vibes with medieval weaponry. However, the Saiyans still alive in this area that the characters face are more reminiscent of what the earthlings know about them and offer an amazing training program for preparation against the enemies.
DB Episode 129 - The Time Room
"The Time Room" sends Goku to the past, where he meets Master Mutaito and younger versions of Roshi and Shen. Unfortunately, this episode doesn't show Roshi and Shen any differently than how they are in the present timeline, which contradicts multiple statements throughout the series.
However, it is still a fun and vibrant episode. The important lessons of ki manipulation that Master Mutaito shows Goku are intriguing and lend to Goku's development as a fighter later seen in the 23rd World Martial Arts Tournament.
DBZ Episodes 202 - Gohan's First Date
While some fans didn't enjoy Gohan's school days, those who did found the added filler just as enjoyable as the canon episodes. "Gohan's First Date" focuses on Gohan being blackmailed for not the reasons he thinks.
The episode comes off as very superhero-esque where the hero thinks their secret has been found out. Of course, by the time the episode nears its conclusion the punchline comes--and that's only that Gohan wore panda patterned underwear.
DBZ Episode 174 - The Puzzle of General Tao
While Tao is actually supposed to be dead, his death is never actually shown so it left Toei room to bring him back up again in this filler episode. This episode turns Tao, who was Goku's first real threatening opponent into a comedic gag that Goku overcomes by solving a puzzle.
The episode truly shows the growth of Goku and how Tao is far beneath him now. The filler episode lends itself well to the overall idea of the Cell Saga with its many parallels and references to old arcs, saying farewell to its protagonist Goku.
DBZ Episode 199 - Goku vs. Pikkon
Collectively, the Other World episodes are considered to be great episodes, but this one is, of course, the best. The imagination of the Other World Tournament has spurned many bright ideas with the Dragon Ball franchise throughout the years and has helped add unique worldbuilding to the series, which was a big help to one of the best Dragon Ball movies, Fusion Reborn.
Goku's final battle against Pikkon is both thrilling and well-conceived. It also introduces Goku combining Kaioken and Super Saiyan into one technique, an idea that is later used in Dragon Ball Super.
DBZ Episode 125 - Goku's Ordeal
More than likely, this is the most well-known and loved filler episode in Dragon Ball Z. The idea to have two burly men at the top of a universe with a unique power system who can fly (and one of which can use teleportation) learn to get their driver's license is absolutely ridiculous and so much fun.
The comedy offered here in this episode is just what Dragon Ball fans had been needing and gave realistic reactions to how these characters would be. It's always astonishing to see how well Toei understood the characters and could write them in such goofy ways.
DBS Episode 70 - A Challenge From Champa! This Time, a Baseball Game!
What's so great about this episode, hosted by the powerful gods of destruction, is that it's a good time for everyone. Those who find the Yamcha memes hilarious will find more to laugh about. Whereas those who are big Yamcha fans finally get to see their favorite earthling in action like they had been dying to see throughout all of Dragon Ball Super.
This episode brought more popularity back to the character, but also gave fans a fun interaction of how characters, such as Goku and Vegeta, would play baseball if they were ever put up to it.