I'm not counting Iggy, just singers.

My vote is Meghan, her music is unbereable. Plus she has no charisma, star quality or interesting look

Ariana.

This
https://www.youtube.com/watch?v=nfWlot6h_JM

And this
https://www.youtube.com/watch?v=e-ORhEE9VVg

EDIT

Oop there's a poll

I like them all

they are all kind of cool

Adele is the best tho, then maybe Lana and Lorde and then Meghan

Meghan

WOW I hate or dislike all of them (except Lana whom I LOVE LOVE LOVE), my vote went to Adele.

From worst to best:

Meghan > Kesha > Ariana > Adele > Lorde > Lana

Lana Del Ray.

I vote Lorde.

She's not that artistic to me. Her beats are all simple and sound like they came from Tumblr, and her lyrics are oftentimes cringeworthy. Her voice is average, though she's a good performer.

Ilike all of them bar Lana so here

I quite like all of them so I'm going with Adele because her music is the most boring, as is her image and videos etc.

Um Iggy was a bigger IT girl than Meghan.

So I choose Iggy

They're all pretty good, but Ke$ha from all of these. Had you included Iggy like you should have, she would take worst hands down.

Kesha is the worst out of them but I like them all

Iggy. From the poll Kesha

Ariana

Iggy isnt a singer.

Ariana is definitely not the "breakthrough" girl of 2014, that belongs to Iggy. But she's the worst on this list, by far. Kesha is quite close, though. It was tough, they both make such terrible music.