The best portable mp3 player will not be the same to everyone. Depending on the features you require, the best portable mp3 player for you will most likely be a different model then the best model for anyone else.
The best portable mp3 player must adapt to whichever functions you need: does it need to carry a lot of music? Does it need to be small and light? Does it need to have a specific battery life? All those factors must be taken into account. Of course, ideally, a perfect mp3 player would have it all, but while technology doesn't provide us with such a player, we can certainly select the one closer to it - today.
Whether you value capacity over portability or size over capacity, there are models out there that will provide you with everything you need. Whichever you choose, the best portable mp3 player certainly is an amazing piece of technology that will allow you to enjoy endless hours of music.