Had a Congo but sold it after two years or so. Just too shallow a rule set, and I got the super jackpot in two days...then wondered if there was anything more. There wasn't. (LOVED playing catch with Amy, though!) Great in a larger collection or temporarily in a small collection.
Shadow is an amazing playfield layout with the awesome sanctum magnet and multiball. But you have to get Aurich's translite so you don't have to stare at Alec Baldwin. Super fun game. Also great in any collection with more lastibility than Congo.
BSD is the hardest of the three with the Mist Multiball...one of the best gimmicks ever. It's a game that will kick your ass and make you want to come back for more.
All great games, but if all three were being offered to me for 3k and I could pick one, I'd go with...
Ah, I can't decide!!!