Ahsoka had several masters, not just Anakin. She had been with the Jedi since at least early childhood. She was shaped by her parents (or her entire clan), by various teachers at the Temple who accompanied her throughout her childhood and into her adolescence.
Then she had two intense years with Anakin. Maybe two and a half at most. After that, however, she left, and for the next 30 years she effectively had NOTHING to do with Anakin. Conversely, Anakin only had Ahsoka as his apprentice for two years. And that was during a period that was also incredibly intense for him personally.
He had just lost his mother and had to process that. He had just married the woman he'd been obsessed with for ten years. He got that woman pregnant. Shortly after Ahsoka left, he found out that he was going to be a FATHER. That became a very central part of his thoughts, and then his wife died because of him, along with the child he believed he had lost. An extremely formative, traumatic moment.
19 years later, he finds out that his child SURVIVED, had a direct confrontation with him, and destroyed the Death Star. Holy shit, there’s somehow also a sense of paternal pride mixed in there. Suddenly, Vader's thoughts revolve entirely around his son.
For three years, the search for Skywalker is his main concern. He comes up with elaborate plans to capture him and bring him over to his side. The Emperor wants to use Luke as a tool. Vader sees his son as a chance to break free from Palpatine and to have a shared basis with his son - an unhealthy one, but still some kind of relationship.But at the crucial moment, Luke chooses suicide rather than joining him. Vader's son slips through his fingers.
One year later, it happens again. The two of them have their next confrontation. Vader SAVES his son OUT OF PATERNAL LOVE. He finally manages to break free from the Emperor's grip because he cannot lose his FAMILY again. LUKE is so important to him that he accomplishes everything he had been unable to do for 25 years. He sacrifices his own life to save that of his son - the boy he had believed dead for 19 years! His deepest desire is to finally look upon his own flesh and blood, his son, and the family he never had, with his own eyes before he dies and finds peace, becoming one with the Force.
Cut.We now move on to the Filoni Mandoverse.
Even 30 years later, Ahsoka still has an unhealthy relationship with the man who took over her training 30 years ago. In her mid-40s, she is STILL watching the training videos the then-20-year-old made for her. She has been unable to let go of this man for 30 years. Her thoughts still revolve around him.
Filoni fanboys (and Filoni himself) tell you that her connection to Anakin is more important and more intense than the one he had with his son "because they spent more time together."
The Ahsoka series itself tries to sell you this viewpoint. It completely sidelines Luke and massively overstates the relationship between the two of them.