I view it as almost a commodity. Stripe does offer some unique value, like their Connect piece (https://stripe.com/docs/connect). Paypal pro has more flexible fraud controls, though many of them are extra cost.

Either is fairly easy to integrate, and if you're running an out of the box ecom package, likely already done for you.

I could probably get slightly better rates with an actual merchant account, but it's a confusing road to go down, with lots of intentionally overcomplicated models.

My biggest beef, as a seller, with cc processing, is the unfair nature of chargebacks. We don't get many, but the system is so biased towards the buyer that buyers can (and do) get away with straight up fraud. My second beef is the scam of rewards and miles cards. The "rewards" are funded entirely on the backs of the merchants.