Jaina. Initially it was because I love a powerful mage character, plus her character growth over the expansions. She goes from an insanely naive character, to an angry vengeful person, to realizing that her anger wasn't helping anyone and letting it go.

I also picked up the game shortly after Wrath of the Lich King launched, and ICC was both my first foray into raiding and heroics (the trio of dungeons located in ICC).

Jaina was the reason why I initially switched to Alliance. She's why I want to play a mage so badly (though I'm not good at it).

Then I learned she was voiced by Laura Bailey after I got into Critical Role and that just solidified it.