Well, any new programming language is fairly easy to grasp once you know one, but there are more similarities between C and NWScript than there is between Python and NWScript.
I'm not sure I would recommend an object oriented programming language as the first language though. They have yet another layer of abstraction and encapsulation, that are hard to use without having some notion of object oriented design. For that matter, I'm not sure I would recommend C as the first language either.
Here are some pros and cons of the different languages:
C is perhaps one of the dirtiest languages around. You can do anything you want to do, but it's easy to make mistakes, and mistakes are punished severely. C is great for programming operating systems, low level drivers, protocol stacks, etc, not so great for large projects involving many programmers.
Java uses C syntax for simple statements, but removes some of the powerfull features of the language, and adds other features. It's an object oriented language, so there is a level of data encapsulation that is great for larger project. Compiled Java code can not run (natively) on a computer, but can be executed in a Java runtime environment, that is a virtual computer that runs on your normal computer. This construction gives Java great portability, since you can get a Java runtime environment for a lot of different computer architectures. So you can write one program, and it will run on a windows machine, a Linux machine, a Unix server, etc. Perhaps the greatest boon of Java is the extensive and well documented library. Java is great for writing flashy programs that manipulates data slowly, e.g. word processors, graphical interfaces for other programs, etc.
If I remember correctly, then Python is a scripting language. That means that the program is not compiled into an executable, but an interpreter reads the program at runtime and executes the instructions. This gives Python the same cross platform capabilities as Java, since you can get interpreters that run on almost any hardware and/or operating system. Python is an object oriented language, and is the language of choice for scripting for games, i.e., the main engine is usually written in C or C++, and the programming that has to be done for the individual levels is done using Python. I've heard good things about Python, but I haven't used it myself.
If I should recommend a path that would make you a competent programmer I'd say something vague along the lines of:
Learn C. Then read some books about object oriented design and object oriented programming. Then learn Java or C++. (Iterate until competent.)
If you "just" want to script for NWN I'd recommend you start scripting using NWScript.
For example, there are no pointers in NWScript, which is most likely a good thing. Pointers allow you to access memory, and to build more complex data structures. It's also the most common source of errors in a program written in C. NWScript is designed for safety, so they didn't include pointers.
DYNAMIC MEMORY ALLOCATION? VOICES IN HEAD.
But, is it (thread-) safe?