As you might imagine, we had a lot of conversations about the right way to teach parallel computing using GPUs. Three things to note, my opinions here only. I think anyone who's programmed in both would agree that CUDA is simpler, particularly at the outset; setting up a "hello, world" kind of program on CUDA is just a lot easier than with OpenCL. Also, I think once you understand either CUDA or OpenCL, it's a piece of cake to pick up the other one; learning the first one is a lot more challenging than learning the second one, so I imagine anyone that takes the course and then wants to pick up OpenCL will have little difficulty. Finally, the ecosystem around CUDA is just a lot more developed than around OpenCL, so if students want/need to go grab a parallel sort routine or scan or other primitives, they'll have a lot easier time in CUDA than in OpenCL, which is important as they start writing more complex programs.
In my research group we program in both CUDA and OpenCL, and we get significant funding from both Intel and AMD who are both OpenCL-focused; but I think I would accurate in saying that strictly from a technical perspective, all my grad students would prefer to code in CUDA if they had to choose.