The most iconic singer is Christina Aguilera. Say what you will about her technique (and I'm sure you will if this doesn't get closed), but her vocal style during 'Stripped' and 'B2B' are constantly emulated and replicated by younger singers and many cite her as an inspiration.

The most iconic overall performer is Beyonce for obvious reasons

Britney is the only answer. She was a cultural phenomenon from 1998-2009.

Of these, Britney has had the most iconic moments.

Britney Spears and Hunter Hayes

Beyoncé of course. Queen of music

Britney or Beyonce, depending on where you live and probably what race you are too

Rihanna and Britney

Picked Rihanna cause Britney's peak was in 1999.

britney

britney spears duh

Probably Britney. Maybe Rihanna or Katy in a few years.

A bit exaggerated

Lady Gaga