I've used Braintree extensively (and have limited experience with Stripe).

Braintree has been an absolute pleasure to develop with. Their support has been excellent, we even had a conference call with their dev team in Australia regarding a new feature that they were rolling out so that we could be an early adopter.

HN gets all giddy and excited about Stripe for some reason, but Braintree is just as nice and easy to use. Stripe doesn't have anything inherently better than BT.