My vote goes to Asset Management: Trade Processing and Settlement
Since traditional trade processes within asset management (where parties trade and manage assets) can be expensive and risky, particularly when it comes to cross-border transactions. Each party in the process, such as broker, custodian, or the settlement manager, keeps their own records which create significant inefficiencies and room for error. The blockchain ledger reduces error by encrypting the records. At the same time, the ledger simplifies the process, while canceling the need for intermediaries.
And what are you going to do when someone hacks your wallet and steals your assets? Or if you lose your wallet backups? If your answer is "nothing", then no government ever would approve such system, and without governments approval these blockchain assets won't have any legal power. And if you'll try to solve those problems, you will end up introducing those third parties right back.