Well. It's the sum of the total device, of course. The touch screen technology, the physical screen itself (material etc.), and the hardware and software that interprets the signals from the touch screen (the quality of the original signal, how the drivers possibly filter the signal to get something more reasonable etc.). Out of the mobile devices that are publicly available that I've tried (and I've tried many, for understandable reasons), the latest Apple iPhone for me provides the most comfortable total touch screen user experience, and by some considerable margin. The capacitive screen isn't of course the only piece of the question, but it is an important part nonetheless.