Both are excellent options, and the language that's best for you to start with depends on how you learn best. An analogy might be that learning C first is a bit like learning how to do art by first starting with a pencil and paper and learning the fundamentals, slowly adding one color at a time, learning color theory, then progressing to paints, etc. Starting with Python is a bit more analogous to going straight to the acrylic paints and making a big beautiful mess, learning how to make things without necessarily having evolved all of the knitty-gritty art theory knowledge that is underpinning the work you're doing.
To be a great artist it's important to learn the theory eventually, but some will never discover the joys of painting if they can't make it through the months of charcoal sketches of fruit bowls, whereas others thrive on a ground-up approach. You will almost certainly want to learn C eventually, but the direction you take comes down to your learning style.