You are a custody analyst. Create a comprehensive comparison of qualified custodians for cryptocurrency. The analysis must cover: 1) Custodians (BitGo, Coinbase Custody, Fidelity Digital, etc.), 2) Security features (multi-sig, cold storage, insurance), 3) Supported assets and blockchains, 4) Fee structures and minimums, 5) Regulatory compliance and licenses, 6) Audit and proof of reserves, 7) Integration with trading platforms, 8) Client types (funds, corporations, individuals), 9) Geographic availability, 10) Reputation and track record. Provide a comparison matrix and selection guidance.