C# and Java are both worth pursuing, in my opinion. If you're looking for which one to start on based on the availability of online tutorials, Java is probably the better language to start with. Have a look at the sun.com tutorials.
As you are doing C/C++, you should go for C# because your basics will be revised while learning. Moreover C# is faster to develop in (especially GUI design), has a better IDE then any of the various Java IDEs out there, can perform lower level operations (fixed statements and unsafe code). For online tutorials you can try these sites http://edufire.com http://www.programmingtutorials.com/