I rank them like this:
But considering your lineup, Sanchez would probably be the best fit as you could use the steals. Don't drop Bradley though. He'll help in steals as well and give you solid numbers across the board. If he ends up in a bad situation where playing time is an issue, then you can consider dropping him. But wait and see. You'll probably regret dropping him if you do it now. Aurilia is probably the one to go. You don't need him with Renteria, and if Renteria gets hurt, you can probably grab him back or someone comparable, as there has to be some decent SSs available if those kind of OFs are free agents. So hang on to Bradley and grab either Sanchez (biggest need) or Burrell (best available).
"I'm telling ya, he jumped us. Gloves off, stick down, no warning. He challenged the Chiefs. Called us names. But Dave was there."
"Dave's a killer."
"Yeah, Dave's a killer."
"Dave's a mess."