Neither is going to help you learn C++, especially since both are pure C APIs. You might be better off trying to use C++11 features or boost. While it's not a big difference, SFML might be a better choice than SDL in that regard as well.
In addition to what Trienco said (he's very right about the difficulty in learning C++ when using C libraries), C++ itself has no understanding of graphics or windows. I'd actually suggest you take a step back and work on a few console-only programs first with pure C++. Focus on learning C++. Then focus on learning different libraries and APIs. You'll find it quite difficult to learn how to use SDL or anything else if you don't yet understand the language you're using it in.
Thanks, to you both.
I actually have a book for learning c++ from the maker of c++ himself. I'll put that to good use as well.