I only liked Jadzia when I rewatched, although she does have some
awful episodes. After the character was revised, she really became the heart of the station. Everyone loved Jadzia. Gambled with Quark, sparred with Worf, geeked out with Bashir, got Kira into dating, messed with Odo, and most of all formed a great friendship with Sisko.
I think it's quite a clever retcon. The writers seemed to get that a centuries old being with numerous previous hosts would be the exact opposite of that original wise and distant Dax - instead, she has a devil may care attitude, zero prejudices, fantastic interpersonal skills. She just wants people to be happy and is generally willing to work around their points of view. This is best seen in her friendship with Quark.
This is why I
wouldn't want her back in season 7. Killing Jadzia should have been a great way to set a darker tone for the final season. She was pretty superfluous in terms of plot, which might be why she had some of the weaker episodes, but she was an absolute rock for the crew. Losing her should have had impact.
But instead we get Ezri, who is perfectly summed up by TribbleFeeder:
Ezri had no depth at all. She was just a 90s-quirky-bubbly fill-in character. She might as well have been on 7th Heaven or Dawson’s Creek.
Honestly, bravo. Ezri was almost a Manic Pixie Dream Girl. Seemed so out of place in VOY, and having her around really screwed up the impact of Jadzia's death when she stepping in as 'counsellor'. Worst of all, she in no way seemed like a character with centures of memories jostling around in her.