It depends. Though CPU and CUDA baking result in identical qualities, there are differences:

• CUDA baking is usually faster than CPU baking with high-end graphics cards.

• CPU baking is available on all computers, whereas CUDA baking is available only on machines with CUDA-enabled NVIDIA graphics cards.

• If your graphics card is simultaneously used for the monitor and CUDA baking, the computer might lag until the baking finishes.