There isn't a single "best" high-risk payment gateway—it depends on your business type, target countries, expected processing volume, chargeback profile, and whether the provider is willing to support your business category.
When comparing providers, I'd pay close attention to their underwriting process, reserve policies, payout schedule, and how they handle chargebacks, as these factors often have a bigger impact on day-to-day operations than the advertised processing rate.
It's also worth checking which countries and currencies they support, how well they integrate with your platform (such as WooCommerce or Shopify), and what kind of customer support they provide if issues arise.
If you can share your business category, monthly processing volume, and the countries you sell to, members may be able to suggest providers that are a better fit.