User blog comment:TheCarrotSaysYumYum/Why Lisanna is Fairy Tail's worst character~/@comment-7418318-20140104100259/@comment-7418318-20140104104915

Ooba and Nichiya at least fulfill rather unique roles, while Lisanna, except for what she did before dying, is completely redundant. And what's more important, they have no detrimental effect on the story (except for annoying or disgusting some people) unlike Lisanna (see Carry's analysis).

Nichiya: He shows that not all Extalians are unified in Earthland, since he left the other Extalians to live at Blue Pegasus. He shows that Exceed don't exclusively partner with Dragon Slayer. He shows that Ichiya can care for someone who isn't a good looking female (not that we ever wanted to know that, but it's still there).

Ooba: The only confirmed (and still living) female Guild Master.

And Lisanna? Let's see:
 * Magic: Another vairation of Take-Over. Counting Jenny, that makes 4.
 * Appearance: Yet another hot babe. Plenty of those around already. She even shares the almost exact look with Yukino.
 * Role #1: Another weak backgound mage. Plenty of those already in Fairy Tail.
 * Role #2: Strauss Sibling. Well... they already have each other, so bringing in (or back) a third one is again redundant.
 * Role #3: Damsel in distress. Lucy fulfills this role far too frequently and "proficient" for my liking already. Besides, it's a role that can be fulfilled by literally anyone, including strangers.
 * Role #4: Love interest for Natsu. Not happening. Neither even hinted at having romantic feelings for the other since her return.
 * Role #5: Fairy Tail's dearheart. She might have been that before her death, but since she returned the others don't seem to care about her all that much. Lucy on the other hand seems to fill that role now.

Did I miss anything? Ever single aspect of Lisanna's character is already fulfilled by at least one, most of the time even multiple other characters. Except for small details, like the exact take-over shapes she has, there is NOTHING unique at all about her.

TL:TR: Lisanna is completely redundant in every aspect since she returned, while Nichiya and Ooba each bring something unique to the story. No matter how disgusting or annoying they might be, they still serve more of a purpose than Lisanna, which makes them better characters.