So close.
I lean toward Paddle.com but they are more for SaaS than stuff like eBooks. They've also changed their website so I don't know if they allow selling anything other than software anymore, but I haven't checked to verify one way or the other either.
Gumroad has an affiliate program which is good, but it still sounds like you are responsible for sales and VAT taxes. It says they will remit VAT taxes in the EU, but I'm not clear whether or not you would have to file any paperwork with the EU for that. Also, it sounds like you'd be responsible for sales taxes in the U.S. for fifty states and hundreds of taxing districts.
Gumroad's fees don't seem unreasonable, but I wish they did the same as Paddle. When you use Paddle.com, Paddle is the merchant of record. That means they handle all sales and VAT taxes and you don't have to deal with that at all because they are the seller, not you. If Gumroad did the same, it'd be like sign me up!