Which PSP handles crypto volatility well?

I'm looking for a new PSP to manage payment gateways for $BTC and $ETH, especially during periods of high market volatility. I've found that many PSPs have issues with slow settlements or delays that cause funds to be held longer than usual, leading to cash flow problems.

Which PSPs have friends used that they feel have good processes or stable systems capable of handling volume and price swings well? Fees are important, but reliability and liquidity are top priorities.