From that list, here is how I see it.
Gone: Colt Anderson, Taiwan Jones, Joe Webb, Brandon Tate, Mike Tolbert.
Re-Signed: Leonard Johnson, Jerel Worthy, Deonte Thompson, E.J. Gaines.
As for the others:
Kyle Williams. Seeing how much help the Bills need at DT, and how much of a leader Kyle is, will they try to convince him to stick around for another year or two?
Cedric Thonton. If Kyle chooses to retire, then re-signing Thornton would be a good idea. Solid not spectacular veteran player, and won't cost much to keep.
Jordan Matthews. How big of a contract will he demand? Pairing Matthews with Kelvin Benjamin would be very beneficial for the Bills, and would lessen the need to draft a WR with a high pick.
Preston Brown. Is he the long term answer at MLB? Does he get a big contract or a "prove it" contract?
Ramon Humber. 30 year old veteran player that has finally made it in the NFL. Tough call to make, especially if Milano progresses the way he has.
Shareece Wright. Another 30+ year old player that is not a starter, and will probably not get that big of a contract.
Seantrel Henderson. He could be good depth, and he's only 25. Should be cheap.
Shamarko Thomas. A young player that is more for depth. Inexpensive to keep.
Travaris Cadet. Another inexpensive player, that might be worth keeping around for training camp.