"Sincona" collection is allegedly the remnants of Sodermann collection. A lot was sold in the Sodemann sales (USB #6(gold), Hess #39, etc. Where did these nice Sincona things come from, I do not know. What I did notice, however, was the fact that not all coins posed as from that "Sincona" collection, actually belonged to that collection...
I am not sure what you mean, when you use the term "unique". To me, it is if only 1 coin is known to us. Like, 1743 horseman kopek, or 1755 large head portrait kopek...
I personally liked the Fuchs collection for variety, the Hasselgesser for rarity in amazing condition, Goodman for exceptional proofs, Brekke for completeness of the copper run, Tolstoi for rarity, wonderful patterns and some beautiful coppers, Hermes for hidden rarities, Bakken and Kruse for insane fakes :-)... You get the idea :-)
I do not think the value of the collection lies in the number of coins. Every serious collection has something that makes it exciting. Whenever someone asks me how many coins I have in my collection, I just smile. However, maybe this question is more valid than I thought....