This is Anakin still learning to be Vader. And Vader still trying to 'kill' Anakin. Any half-decent set of writers would have started by exploring that.
In Rebels, specifically
The Twilight of The Apprentice Episode, we see Vader's mask break. His eyes, for a split second, are normal, and he calls out to Ahsoka in Anakin's voice. For a moment, we see his struggle. It is one of the best Star Wars scenes across all movies, animated series or spin-offs.
Anakin's connection with Obi-Wan was far far stronger than with Ahsoka, it's the reason why the hate exists as well. I would have loved it if it instead of being a senseless hate-filled monster, we saw a little internal struggle. For the first time in a decade, there is reason for Vader to ask a question he never could. They could have got that fire to break Vader's mask, distorting the filter. 'Did she die peacefully, Obi-Wan?' They could have used Hayden Christensen's voice, and played Across the Stars in the background, subtly fading away while Obi Wan replied, only to be replaced by Anakin's Betrayal or even the Imperial March as Vader returned, in all his fury.
I would not have minded if they ripped off Kung Fu Panda, even, and plagiarized Tai Lung's dialogues as he fights Shifu.
"When Windu did X, what did you do? Nothing!'
"Everything I did, I did for you. Who filled my head with dreams? Who watched as Padme died?
"Tell me how proud you are, Obi-Wan!"
Anything that reminded us of the tragedy. Of the distance between what is, and what could have been. Such poor poor writing, unfortunately. They have no idea what makes Vader work, and are simply overdoing the Force Choke in every scene he exists so far. No subtlety at all.
A rather long video for how things worked out in the comics for new Vader: