I have spent the better part of 10 years with C, and it was my
first serious language. I would say go with D if you just want to
work on higher level projects and forego the low level details to
an extent. C is very low level and very unforgiving. The
inexperienced will run into things like segmentation faults or
other memory errors until they understand how pointers and memory
works.
Also, while D has fewer available resources than C does, C is
also an entirely different beast. The C standard library is very
limited, only providing some very basic functionality. Advanced
data structure implementations are not provided by it so you
would be forced to either write your own or use a suitable third
party library. Contrast this with C++ or D where such things are
likely already provided by their standard libraries.
In short, C is generally used to implement a foundation of sorts
for higher level programs or other ventures where low level
control is a requirement. For example, it is common to implement
general purpose libraries for things like compression or
encryption in C for performance reasons and also for reusable
code. Libraries written in C can generally be used by any
language that runs natively, usually through a binding or a
translation of the library API.
