I think Werth is your best bet here. You really don't need to take another pitcher this early when you have Halladay locking you down, so take the best slugger on the board: Werth.
I wouldn't blink at Feliz right now, given the uncertainty in the rotation still. He is supposed to start another game tomorrow, and they had Ogando pitching the 9th earlier today. I still think he ends up in the pen (wrong choice, but that's another thread), but I wouldn't take the risk. He still has value as a starter, but it would probably shift him down to more the phil hughes, john danks, danny hudson range (this year). Look at it this way, you're essentially just starting in the 6th round. Would you normally draft a closer in the 6th round? I hope not, because even your Mo Rivera, Bell, Wilson and Soria types aren't going off the board until later than that in most drafts. Take advantage of your opponents jumping on later picks with keepers and snatch up the 4th rounder that's still around *way* too late.
Rollins is an intriguing option, given the relative scarcity at SS, especially if Reyes, A Ramirez and Andrus are kept, so that is the other one I would consider, but I would opt for the best player left on the board still: Werth, by a good margin.