TLDR; This card is great a mitigating failure, which is going to happen (especially on harder difficulties).
Any effect that lets you "dig" for cards is a great include, and this version of Rabbit's Foot really shines on harder difficulties, acting as a catch-up card. Playing on Hard or Expert really teaches you to "pick your battles" when it comes to skill tests. Failing happens, and If I'm playing Hard and am already 3 down on a test with only 3 icons to commit, I'll save my cards for a future "battle" instead of hoping for that 0 or Elder Sign from the chaos bag. The only exception to this IMO is a Treachery with a "...for each point you failed by" effect.
This Rabbit's Foot mitigates the failure by allowing you to find the best card from the top X of your deck. It need not be the best card in your deck, but anything is better than that weakness that always seems to be lurking right on top after an especially painful failure.
I also like that this is a 3XP card. It's made for Survivors and can't be splashed into non-Survivor decks like its Level 0 counterpart (which is a decent splash card for any who can take it because, again, failure happens).
Wendy Adams is the only Survivor with direct competition for the Accessory slot (at least with a signature card), but the class has so much recursion that I might only use her Amulet for the icons anyway, especially on harder difficulty.
I'd probably prioritize Police Badge with William Yorick, but it's meant to be discarded (and recurred) anyway, so there's no reason to not sleeve Rabbit's Foot as well.
Silas Marsh likes this card because you can commit a Skill card and if you're going to fail anyway after drawing the Chaos Token, just use his Reaction to pop the Skill back to your hand and dig a little deeper into your deck for another card.
Expect to fail some tests with Calvin Wright until you get him going, and this card will help him get going. You want Calvin to "ride the line" with Damage and Horror, so this is an especially good Accessory to replace Cherished Keepsake when it has 3 Horror on it so you don't have to exile it, or dig for something to replace Leather Coat for the same reason.
This card obviously is amazing with Stella Clark and her Reaction.
"Ashcan" Pete will like this card to dig for a card he doesn't mind discarding to ready Duke: A Glimmer of Hope, Improvised Weapon, Impromptu Barrier, Winging It, etc., if you're playing them, or something like Resourceful or Scrounge for Supplies to get something back.
Rita Young might like this with her 2 Intellect.
=== EDIT ===
Patrice Hathaway doesn't really need this card, as she is always going to have a hand full of cards to throw at a test. (Thanks StyxTBeuford for pointing that out!)
Lola Hayes can also play this card and, while she would benefit from it, it's not going to trigger for her as often as it will for others when she finds herself in a non-Survivor role.
This card is great a mitigating failure, which is going to happen (especially on harder difficulties).