I’m looking at this problem now too. I looked at Stripe Billing, Chargebee, Chargify, Paddle and Recurly. My requirements are a bit different in that I wanted to run the payments and accounting through my own product (Fragment), but wanted something to handle the subscription logic. None of those fitted the bill for various reasons but the biggest one being they are all very card-focused and I wanted to use ACH because of the much lower fees (we do a few big transactions vs lots of small ones).
We use Octane for usage-based billing, which has some subscription management built-in so my current plan is to have Octane generate invoices each month and build a little retool app that takes those invoices, updates a customer-specific Notion page with it, and calls the Fragment API to bill the customer over ACH.
The missing piece in all this is tax (calculation, tracking, payment, filing), which is solved by various combinations of Stripe Tax, Tax Jar, Paddle et al. Octane are working on adding some simple tax calc functionality at my request, but I’ll need to figure out the tax rate per customer and track how much we’ve tax we’ve collected per US state (probably using TaxJar)