**Stripe**, if I have to pick one blind.
The reason is coverage of the likely case: unless you're processing serious volume or running physical stores, Stripe wins on developer experience, documentation, speed to launch, and product breadth (subscriptions/Billing, Connect for marketplaces, Radar for fraud, Tax, Issuing). You can be live in an afternoon. Adyen historically hasn't even wanted merchants below a certain size, and its onboarding involves actual sales conversations and contracts.
**Where Adyen is clearly the better choice:**
- **High volume.** Adyen prices on interchange++ plus a small fixed fee per transaction, which gets meaningfully cheaper than blended rates once you're at scale. Stripe will negotiate too, but Adyen's structure is usually more favorable.
- **Omnichannel retail.** If you have stores *and* online, Adyen's unified platform for in-person and online payments is genuinely better than Stripe Terminal — this is their strongest suit.
- **Global footprint with local acquiring.** Adyen holds its own acquiring licenses across many markets and connects directly to card schemes, which tends to produce better authorization rates and lower costs than routing through intermediaries. This matters a lot at scale and barely at all when you're small.
- **Enterprise stability.** Fewer stories of abrupt account freezes; more of a relationship-managed vendor than a self-serve platform.
**The honest decision rule:** if your annual card volume is under roughly $10–20M, or you need subscriptions, a marketplace, or fast iteration, take Stripe. Above that, or with brick-and-mortar plus multi-country operations, get quotes from both — Adyen will probably win on economics and auth rates, and the cost difference will outweigh the developer-experience gap.
Two caveats: specific pricing and thresholds change, so verify current terms directly; and many large companies run both, using one as primary and the other as a fallback for redundancy and routing optimization.