I use Stripe exclusively. The integration into Rails isn't too bad (I wrote a book[1] about it and a gem[2] that automates a lot of it) but there are a lot of little details that one might not think of if they've never done a payment integration before.
Recurly][3] abstracts over multiple payment gateways for subscriptions, if that's something you need to do. I haven't used it myself but I've heard good things.
Are you looking for a single integration that handles both PayPal and credit card transactions? Stripe users typically end up integrating both separately (though building a billing abstraction above both).
I use Stripe exclusively. The integration into Rails isn't too bad (I wrote a book[1] about it and a gem[2] that automates a lot of it) but there are a lot of little details that one might not think of if they've never done a payment integration before.
Recurly][3] abstracts over multiple payment gateways for subscriptions, if that's something you need to do. I haven't used it myself but I've heard good things.
[1]: https://www.masteringmodernpayments.com
[2]: https://www.payola.io
[3]: https://recurly.com