I asked the same question a few weeks ago. Coming from a BASIC background with some work with PASCAl and machine langage, I was wondering too. I decided on C and now after I bought my first microcontroller, the Arduino Mega, I am glad I did. Some stuff is written in BASIC for the BASIC STAMP but most of the stuff I run into is for the Arduino and it is all C. Plus C is alot easier to learn than C++ which I could never get the hang of. And what I am finding out as I learn C that the subset of C needed for robots is very easy. I think every here will tell you to go with C.
JC