Reddit reviews Sentry: Reborn TPB

• The Sentry
  
• New Avengers vol. 2: Sentry
  
• Sentry: Reborn

• The Sentry
  
• New Avengers: The Sentry
  
• The Sentry Reborn
  
• Mighty Avengers
  
• Dark Avengers
  
• Siege
  
  Also, as a standalone: The Age of the Sentry

Age of Sentry, Marvel Knights: Sentry or another link and Sentry Reborn.

All three are the best reads. You can also pickup the New Avengers series that brings him back but STOP after he is brought back. All of the writers have no idea what to do with him and end up destroying his character.

:)

EDIT: Link to brand new copies