I've been most happy with silver uncirculated sets and proofs I've built/collected over the years. IMHO, it's hard to go wrong with BU or proof US silver coins having small premiums over current spot.
If looking for a little physical silver to put back, I like old junk halves that aren't too worn. For some of us it's hard to shake the collecting bug even when hoarding silver. There's nothing wrong with fresh new ASEs if the premium isn't too crazy.