What is the fastest way to pick up a sample form ADC: poll loop, ISR->GetValue or DMA->ISR? I bet it's still old good classic poll loop?
If you want to immediately process the value of the ADC, then the ADC's ISR would be the fastest. If you are going to transfer the content of the ADC to a buffer or any other perripheral, then the DMA would be the fastest.
Polling coule be fast if the processor is not involved in any other operation and spends all the time polling the ADC.