Star Wars: The Clone Wars added another emotional layer to Ahsoka Tano and Darth Vader's duel from Star Wars Rebels. In Clone Wars season 7, episode 9, "Old Friends Not Forgotten", the master and his apprentice reunite after months of her self-imposed exile. Their final interaction is brief yet heartwarming, contrasting the nature of their final encounter many years later. The next time they see each other is during the events of Star Wars Rebels, where they would clash lightsabers for the first time. Clone Wars season 7 made this duel all the more tragic in just a few small but emotionally-charged scenes.
In Clone Wars season 7, episode 8, "Together Again", Ahsoka and the Martez sisters narrowly escape the clutches of the Pyke crime syndicate. Once they safely return to Coruscant, they are confronted by a band of Mandalorians led by Bo-Katan Kryze, who needs Ahsoka's help. Darth Maul rules over Mandalore, which Bo-Katan wants to put an end to but can't without more allies in the Republic. Ahsoka is hesitant to return, especially to the Jedi, given the controversial circumstances of her season 5 departure. She ultimately decides to jump back into the fray by the time the next episode rolled around.
Clone Wars season 7, episode 9, "Old Friends Not Forgotten" opens with the two speaking with Anakin Skywalker and Obi-Wan Kenobi to acquire some much-needed backup, which the former happily provides. He presents Ahsoka with not only Captain, now Commander Rex but also a whole battalion of specialized 501st troopers to aid her in the Siege of Mandalore, but the surprises didn't stop there. He also offers her a refurbished set of lightsabers, as an unofficial welcome back to the Jedi Order, which she graciously takes into battle. The moment is touching and rekindles the bond Ahsoka and Anakin had in years past. The quick reminder of their friendship retroactively makes their Rebellion-era fight harder to digest.
When their duel goes down, both characters are a far cry from their Clone Wars selves, physically and emotionally. Ahsoka went into hiding following Order 66 and took up a life as a hardened Rebel operative under the codename Fulcrum. Meanwhile, Anakin's life took a dark turn, becoming the terrifying cyborg Darth Vader and running the Empire alongside Emperor Palpatine. Bearing in mind "Old Friends Not Forgotten" showcased their final interaction as friends brings so much more emotion to their meeting on Malachor years later. They parted ways on such a positive note, after a long period away, only to be separated again before their deadly encounter.
There is no right or wrong answer when discussing which animated program is superior, as the question is subjective. The truth is, The Clone Wars and Rebels work in tandem with one another, playing to each other's strengths when telling stories. This case is no different, with Anakin and Ahsoka's relationship being used as a talking point for totally distinct reasons. Star Wars Rebels played off of the dynamic that The Clone Wars carefully set up for years. Knowing how the Star Wars timeline goes, the two Jedi needed to have a final meeting as allies before becoming enemies. It just so happens that presenting such a scene made an already heartbreaking action sequence even more so.