Originally Posted by Zubasa
Well there is hardly anything that uses OpenCL yet, in fact ATi haven't release drivers that enables OpenCL and DirectCompute on older cards.
"Older" includes all the HD3k and 4k series.
Stream is in a even more pityful state, I hardly knows any software that supports it apart from stuff from Adobe.
Not to mention that CUDA has Visual Studio integration and many more tools, profilers, debuggers...
It's also a high level language* and that makes easier to program for than the other ones which are low-medium level languages.
Nvidia did really put a lot of effort into GPGPU since G80 days and it's really paying off now.
*You can still access low level if you wish, you can get pretty close to silicon.