Payment Platforms Question

Hi all,

I'm working on setting up an e-commerce solution for my website. It's been a hobby project of mine for some time, done in ASP.Net and SQL Server. I have been looking for a good solution for setting up both a recurring payment solution for membership to the site, and also within the same site the premium users will have access to a marketplace where they can sell their creations to other members of the site. I see that Stripe and Braintree both offer the features I need to set this up, but BrainTree is paypal focused, while Stripe doesn't handle PayPal at all. At the moment I have a sandbox account with PayPal and am using IPN to log transactions to my local database. I don't mind swapping that out for a better more reliable solution (IPN doesn't seem to have the best reputation), but want to make sure that whichever way I go the implementation will be reasonably straightforward to handle (I'm the developer of the site, so technical implementation is something I can handle, so long as the documentation is good and there are examples I can go off of).

I also notice that the BBB gives Stripe an A+ rating despite it having a large number of negative reviews, but BrainTree gets a B+ though it has very few negative reviews. That's confusing. I'm wondering if anyone here can offer any insights and/or recommendations on which of the two might be better, with a little bit of information as to why you think so.

More specifically here is what I am trying to accomplish:

Payment System Requirements
---------------------------

Note: USA Market Only

1. All payments go to my business checking account.

2. My site will have the following commercial aspects:

a) Subscription Service with several possible levels:
Free
Basic
Premium (access to the MarketPlace where authors can create their own goods and sell them to other members at a price that they set)

b) Some digital or Print on Demand items through 3rd Party sites and through my website as well.
i) Books that I have authored
iii) Fun & Promotional T-Shirts via SpreadShirts.com (or similar company)
iv) Digital POD products that I have authored to be sold through 3rd Party Sites such as Amazon, Lulu, etc.
- Books
- Card Deck
v) Original artwork sold as Posters, Prints, Framed pictures, Mugs, etc via DeviantArt or similar site.

Coupons and Promotions for Digital Products should be possible to set up.

c) Digital Marketplace
i) Allows Premium Users ("Author") to create a digital product that can only be accessed through my web application (it is a game system)
and set a price for them to sell to other members (all levels) of the service.
- my company gets some percent (20%)
- Authors get the remaining percent (80%)

Coupons and Promotions for these digital products in my system should be possible to set up.

2. The solution must:

a) Allow me to configure payment prices and add new payment options, coupons and promotions without too much trouble.
b) Provide good customer service for purchasers.
c) Provide good merchant support for myself.
d) The payment system should incorporate Sales Tax (Avalara, TaxJar, or equivalent) though I'm not sure how urgent this aspect is in the early phase.
e) The payment system must allow for
i) Marketplace: Split Payments (aka Adapative Payments in PayPal)
ii) Subscription (Reoccuring Payments)
iii) Digital Products Sales via the Elthos Website
f) Be cost effective in the follow aspects:
i) Reasonably priced to set up and configure
ii) The payment services must be competitively priced in terms of fee structure.

I'm looking for any advice on platforms that might be able to handle these aspects. It boils down to three things:
- Recurring Payments
- MarketPlace (Split Payments) for Premium Members of the Subscription
- Digital Products (PDFs) that may offer discounts (Coupons & Promotions) for subscriptions (ie - 3 month's free, etc)

Any thoughts and/or advice would be greatly appreciated. Thank you!