>I'm not sure which one to go with. How involved is it to integrate these?

I really like https://siftscience.com.

The important thing is to not over-think things; it's rarely that case that you truly, honestly, really need real-time automated fraud detection.

Start with implementing the absolute bare minimum. You'll then receive emails from e.g. Sift when a bad user is identified, and you can manually refund the transaction, cancel the order, and block the user.