Q:

REST API vs Classic APIs

I am working with PayPal integration for the first time and am confused regarding the two solutions.  I need to accept direct payments.   User enters credit card information and I use PayPal as the processor.  I would also at a later point after release like to add PayPal Express Checkout for convenience.  I have PayPal Payments Pro, which assigned me a Payflow account.  Which documentation should I follow to accomplish both?  There are so many assorted PDFs, many of which are over 100 pages, and I don't have a clear idea where I should start. 
I would greatly appreciate a quick separation of services (XMLPay?  DoDirectPayment?) 
I am using C# / ASP.NET and already have the core and rest api libraries installed in my project via NuGet.  I also have an app created and an ID+Secret pair to use. 
I have called PayPal but the phone team does not have the proficiency to answer these questions and simply refers me to the documentation site.  Hopefully a developer who has been down this road can steer me in the right direction.  Thanks! 

A:

I would suggest the REST Apis, they support both direct credit card and express checkout depending on which funding instrument (CC vs PayPal) you pass in the pay request. 
There is also a C# SDK provided to get you started, all info available at: https://developer.paypal.com/webapps/developer/docs/api/

