Paypal's documentation is horrid; they have several competing APIs (the most obvious choice - the REST API - has been silently abandoned); there are many active bugs; their support is slow and unreliable; the admin UX is horrid (finding transactions can be very hard); you will find yourself discovering the hard way how the system behaves on error; and oh there will be lots of errors.
Stripe is stupid simple by comparison, and impeccably reliable.
I pushed thousands of transactions per day through each. Paypal practically required a dedicated engineer to follow up on all the chaos. They periodically lost transactions (and fessed up to it after hours of debugging and support). They lost support tickets too. It's maddening.
If you aren't in a high volume business, Paypal is NOT worth the development headache. You can probably get 20% more users by spending the time building features your users care about.