Pacifica is fine, good even, but vastly overrated. She was only interesting in two episodes and a comic, and the "poor little rich girl" isn't an earthshattering idea or character arc. She's perfectly nice but only stands out because female characterization was pretty weak on that show and because of fandom shit like fetish art and shipping.
Angelica was funny and showed some depth from time to time but her always snapping back to status quo was obnoxious and of course her being an annoying brat was most of her character. Rugrats was never a very deep, multifaceted show anyway in any form. Its characterization was straightforward.
Helga was the best of the three. She had a lot of screen time showing and exploring her different sides and issues as a person, her relationships with family, rivals, and friends, and she felt fairly original and fresh at the time (obviously she is tsundere, but tsunderes don't usually look like her or really act like she does aside from that trait). She is the most interesting of these three characters.