Website freelancers - how do you manage your sites & billing?

I have tried stripe and PayPal for different projects and among the two I prefer PayPal. While they are both pretty good, PayPal is easy to integrate to the front end for me. But if you foresee potential frequent changes to your users' payment packages/subscriptions, then I believe it is easier to automate such changes with Stripe.

Tried a few, seems in my opinion this one really stands apart:
https://www.waveapps.com/
It will:

1. Keep records for you in an organized format. Choose whatever method takes the least amount of time and keeps you organized. For me this was a simple decision.
2. Allow clients to click a link right in the invoice and pay with credit card, etc. Sometimes clients would give me various forms of "the check is in the mail" types of runaround, and this minimized any of that actually being on my end. This feature does charge a small percentage, but was worth it for me.
3. If / when you outgrow this software you will be at a place where you need professional accounting software (Quickbooks, etc.) and possibly someone to do this for you, and up to that point this should get the tasks done for you.
   I am not affiliated with this product in any way. Just my personal opinion. Cheers!