What's the idea payment service provider we are looking for? There will be always a trade-off between flexibility and risk control. On one hand, we don't want o

What's the idea payment service provider we are looking for? There will be always a trade-off between flexibility and risk control. On one hand, we don't want our account be frozen to damage our business. On the other hand, we also don't want our money be stolen due to some fraud action. what's the best example of a payment service provider? I suspect that a payment provider can easily satisfy merchants when they are small (e.g. startup), but will come into the similar situation when they grow up to a big one.