GGGB but when Loud gets re-released with new tracks, probably the current era
For Britney it was probably Blackout or In the Zone

+1

GGGB followed by Rated R

GGGB/A girl like me I loved that Rihanna

Rated R, hands down. No other era can come anywhere near the rawness and just pure darkness of it.

Rated R, But I love A Girl Like Me and Loud. Lol,

Rated R, but I like Loud better.

LOUD

From Britney Spears

"In The Zone"

From Kelly

The Breakaway

From Rihanna

Rated R

Rated R

Like someone said earlier, I see 'Loud' potentially being a very profitable and successful era, but GGGB just had everything perfect. The singles, the release of the singles, the re-release. My only gripe with GGGB is "Breaking Dishes" not been an official single.

Updated:

CIARA

The way you have it lined up.

Goodies

From Britney: In The Zone

From Kelly: Breakaway

From Rihanna: GGGB

From Ciara: Goodies

Goodies by far.

Goodies.

Basic Instinct

Goodies

I must go with The Evolution.