actually, a lot of fans hated Ashoka when she first appeared but as the show went on she became likable and cool.

I think a big contrast is that Ahsoka grew as a character and had a ton of experiences where she nearly died, got scolded and punished for doing rash things, and actually had motivation.

Rey doesn't come even come off like she's in any real danger, the times she did something rash it either worked out in the end or got cut from the movie, and Rey just kinda does things for… reasons. Like at first she wanted to stay on Jakku for her family and the TLJ says she knew they were dead the whole time (Kylo learned this after he looked into her mind so how else would he know about it?) and her motivations are rather weak, like she all of a sudden says there's good in Kylo Ren despite witnessing him murder Han and nearly killed herself and Finn. Where as Luke and Anakin lost limbs, Leia, Obi-Wan, and Ahsoka suffered emotional trauma, Rey is fine and the most she gets is a scratch on her arm and squeezed a bit by Snoke.

While Ahsoka was initially disliked, that went away after a bit as she grew as a character and people freaked out when she returned in Rebels, especially in the last few episodes, basically destroying that sexism claim Abrams tried to pin on the fans. Rey's had two films and she is easily the blandest leading character Star Wars has ever had.

Plus, the actual explanation they had to put out for why Rey is so strong is no feminist victory, they essentially made her a Force parasite.