Ezri Dax is Best Dax.
Let me be specific about that. I generally had no issues with Ezri Dax's character, or Nichole deBoer's acting (although Ezri was a bit whiny for my tastes...).
The problem I had was that they decided to introduce this brand-new character, and have several episodes devoted to her story, just for one season before the show ended
. Dax should have stayed dead, as a casualty of war, and those stories of Ezri's should have been made into Dominion war arc stories. Perhaps that way, we could have had an ending to DS9 that was less rushed.
And "TMOTTH" should just never have been made. Period.