I feel that the VNC protocol gets a bad reputation because of bad implementations. There's really nothing in the protocol itself that keeps it back.
What I like about VNC is that you can actually read the RFC and get fairly a good understanding of it in less than a day. I'm not sure if the same can be said for RDP.
Microsoft has this page where you can access a bunch of PDF documents that describe RDP in some sense, but I've no idea where I would even start and/or what's even relevant for any given problem that you might want to solve.