http://www.officialcharts.com/chart-...em-all__16444/
@ Leona selling 4M albums and 5M singles only in the UK

Fifth Harmony

1D and Olly have sold more records than Leona in the UK?!! Wow I wasn't expecting that.
Little Mix

One direction

1D are split up so they don't count.

Of the currently existing ones, Leona Lewis followed by Olly Murs and Fifth Harmony (about equal) then Zayn then Cher Lloyd then Ella Henderson then JLS then James Arthur then Niall Horan and Little Mix (about equal)

I know it's weird he sold so much singles even tho Leona's numbers aren't really updated as stated in the article "three albums give her 4.06m chart sales". She outsold him big time WW tho.
Anyways can't wait for her "Say You Won't Let Go" size comeback smash soon just without the homophobic comments

1D is the only global one.

1D obviously

1D

1D

Melanie Martinez

It's hard to measure who is truly the most successful as the two acts who were the biggest globally were finished in 5 years or less.

Although Leona had a huge debut era 1D were more consistent with their success so the answer is them.

It's only UK sales
But still they prob didn't pass the 300K mark there

One Direction
Leona Lewis
Olly Murs
Little Mix

X Factor UK is huge especially a few years ago (all the contestants in the list are from 2011 or earlier), obviously the ones from X Factor UK have a huge advantage over international artists who have to start from scratch. Almost every season of X Factor UK produces at least one star, it's just a given. Regardless, 5H have sold around 2 million records in the UK which is not bad at all.

No one wants your opinion when the receipts are in the article

1D or Leona

The article is UK sales only The title of thread is "Who's the biggest X Factor star of them all", not "Who's the biggest X Factor star in the UK". I was ranking them based off global success.