Let's see...
Adam Lambert -
Aftermath. I don't hate it! The problem is that all of his other stuff is SO much better.
Lady Gaga -
Highway Unicorn (Road To Love). It's way too cheesey! It's pretty much the only song I skip by her. But I did enjoy it as the opener to the Born The Way Ball
Natalia Kills - I love them all! Seriously, I don't think she has a bad song.
Britney Spears -
My Baby. Sweet song idea, but the execution is simply terrible.
Ayumi Hamasaki - This is way too hard. Ayu has like a million songs, it's impossible to pick just one.
Rihanna - Most of her first two albums

Her early material is rather blah (with the exception of SOS, Unfaithful, Final Goodbye <3 & Kisses Don't Lie). She hit her stride with Good Girl Gone Bad.
Girls Aloud -
Why Do It?. Bleh b-side.