I use French Kiss in the form of a comedy routine I designed for my stand-up and stage shows, and have never had anyone want to keep the cards as souvenirs. They're folded up and soggy, and as much as some people may think this of themselves, nobody wants your signed card.
That said, I do have a preferred closer. It is one of the most impactful effects in my repertoire, and it leaves the deck of cards in a perfect condition to end the set. Only thing is, I don't want to tell anyone what it is, because next to nobody uses this and I want to keep it that way
All I can say is that it's an effect created by Bill Abbott who I consider one of the nicest, most generous magicians around. When my materials for said effect ran out, I went to purchase it again only to find that it has been discontinued. Luckily, Mr. Abbott popped into the shop that day and I asked him if there was any chance of the effect being restocked. He just had me give him my address, and within a week he sent me two replacements of the effect along with a nice little note and an instructional DVD that didn't come with the product the first time I bought it. Something I'll never forget. That alone makes the effect particularly special for me.