Daniel Munthe Agger

Daniel Munthe Agger

is a Danish professional footballer who plays as a defenderfor Danish Superliga club Brøndby IF and captains the Denmark national team. Agger has been described as "a fine reader of the game, comfortable on the ball and blessed with a ferocious shot."^[4]

He started his senior career with Brøndby in July 2004, winning the Danish Superliga and the Danish Cup, before moving to Liverpoolin January 2006. He made 175 Premier League appearances for the club and won the League Cup and Community Shield. Agger returned to Brøndby for personal reasons in August 2014.

A full international since 2005, Agger has earned over 70 caps and played for Denmark at the 2010 FIFA World Cup and UEFA Euro 2012.

in my opinion Agger is best defender forever for liverpool

Glen Johnson

Glen McLeod Cooper Johnson 

He began his career at West Ham United, spending time on loan at Millwall, and was signed by Chelsea for £6 million after West Ham's relegation in 2003. Following a successful season on loan, he joined Portsmouth in 2007, where he won the FA Cup in the following year. Johnson moved to Liverpool in the summer of 2009. Johnson spent six seasons at Anfield making 200 appearances. He joined Stoke City in July 2015 on a free transfer.

He has also been capped 54 times by the national team since 2003, and was selected in England's squads for two World Cups and UEFA Euro 2012.
In my opinion he is great player in left back for Liverpool.