This is what I would play if I was having a party. It's based on my own personal taste so might not be to everyone's taste but check it out anyway.
Gimme More - Britney Spears
Baby One More Time - Britney Spears
Black Magic - Little Mix
Sound of the Underground - Girls Aloud
The Show - Girls Aloud
The Promise - Girls Aloud
Wake Me Up - Girls Aloud
Freak Like Me - Sugababes
In The Middle - Sugababes
Up - The Saturdays
Higher - The Saturdays
All Fired Up - The Saturdays
Work - The Saturdays
Murder on the Dancefloor - Sophie Ellis-Bextor
Super Bass - Nicki Minaj (I can't stand her but I love this song!)
On The Floor - Jennifer Lopez
Dance Again - Jennifer Lopez
Work Bitch - Britney Spears
Oops I Did It Again - Britney Spears
Stronger - Britney Spears
Piece of Me - Britney Spears
Womanizer - Britney Spears
Toxic - Britney Spears
Just A Little - Liberty X
Just Dance - Lady Gaga
Bad Romance - Lady Gaga
Poker Face - Lady Gaga
Telephone - Lady Gaga
Judas - Lady Gaga
Do What U Want - Lady Gaga
I Kissed A Girl - Katy Perry
Hot n Cold - Katy Perry
Teenage Dream - Katy Perry
Dark Horse - Katy Perry
E.T. - Katy Perry album version is better than the one with Kanye West)
Last Friday Night - Katy Perry
Blow - Ke$ha
Take It Off - Ke$ha
Black Magic - Little Mix
Fancy - Iggy Azalea
Beg For It - Iggy Azalea
Worth It - Fifth Harmony
There's a lot of Britney in there but I am a big fan so I probably can get away with it

Would album tracks from those artists be any good or just singles? I'm trying to stay away from overused cliche party songs (eg Don't Stop Believin', Dancing Queen).