I have now worked on integrating Stripe, Razorpay and PayPal on our app.
While Stripe has an absolute gem of a documentation.
Reading PayPal's documentation has been one of the most torturous week of my dev life.

Stripes business model pretty much revolves around ease of implementation to devs, so expect everything else to be terrible in comparison. There are a few others who aren't bad, but for the most part they're shocking.

One does not simply integrate with PayPal, it's a test of your abilities in its self.

Stripe and others are plug and play, in essence.

GayPal is shit in every aspect, and if you have any chance at all to avoid it, TAKE IT!

The technical implementation is the smallest problem - if you ever had to deal with chargebacks/complaints, as a user or vendor, then you know that GayPal is a throbbing herpes infested cock that should have fallen off years ago.

I hope they finally die.