It's interesting because I had to integrate Stripe's dispute API for a client once and I'm sure the opposite was true - we had to prove the customer was lying, as Stripe would side with the customer by default, not the other way around.

I might be wrong though, this was years ago and I had no involvement in the dispute process itself, but that was my recollection. I'd have thought PayPal would be more pro-consumer if anything because of how consumer facing it is - it's not like they're just doing anonymous CC processing on behalf of the merchant, which is largely what Stripe does.