I'd go with a defensive player like Neal, Burnett, or even Shields (though he already kinda made a "splash").
The only thing I know about Mike Neal is what he talks about on Twitter and the guy is ready to play. He is a beast and is in incredible shape. I'll hold judgement on filling Jenkins' shoes, but I think it could be done.
When Morgan Burnett did play last year, he showed glimpses of great play for a rookie. I expect him to continue improving, especially with the amazing secondary he is surrounded by.
Sam Shields played amazing last year already. With his speed and man coverage ability, I think it will allow Capers to throw around some more crazy defensive looks. Like Burnett, he is surrounded by secondary talent which will only help him more.