roster help! defensive lineman who to keep

Looking for some advice on who I should keep on my dynasty team.
Adrian Clayborne, Ziggy Ansah ,Olivier Vernon, Geno Atkins, Anthony Spencer and Michael Johnson

Hi Bill,

I'd rank them in the following order in dynasty leagues:

1) Ansah
2) Johnson
3) Atkins
4) Vernon
5) Clayborn
6) Spencer

Spencer is the clear out main out in that group right now.