Is there a particular company that anyone would recommend for doing ach drafts, obviously I would be creating the invoice in appsheet, but looking for a service to do ach drafts weekly?
I currently use Stripe services. While I do not integrate with them for invoicing and billing ( I use the Stripe native service), they do have a extensive developers sections to help integrate any other apps or services with their payment services.
I have also used PayWhirl in the past. They are built on top of Stripe, i.e. use Stripe for payment processing, but also provide the capability to create custom widgets that you can generate with your plans/products plus options and then drop the widget into your own services. Their service also includes a customer portal where your customers can view their Invoices, past payments and upcoming payment schedule.
Both of the above services can process ACH payments and both take a percentage of the payment as their fee. In the case of PayWhirl, you would pay a fee to PayWhirl and another fee to Stripe out of each payments processed.
For myself, once I found out that Stripe could do invoicing and payments, which was all I needed, I was able to eliminate PayWhirl to avoid double fees. BUT, I would consider using PayWhirl again if I should ever need the ability to provide a checkout service where customers choose plan options or products.