Comprehensive comparison of crypto payment gateways and protocols. Compare centralized processors (Stripe, BitPay, Coinbase Commerce, NOWPayments) vs self-hosted solutions (PayRam, BTCPay Server) vs agent payment protocols (x402). Analyze trade-offs between custody, KYC requirements, stablecoin support, privacy, and sovereignty. Decision framework for choosing payment infrastructure. Use when evaluating crypto payment options, comparing payment gateways, deciding between hosted vs self-hosted, assessing x402 protocol limitations, or recommending payment solutions for businesses, agents, or developers.