Before I owned the current generation ipod's I definitely had the above question which one is the best? Which one of the current generation Ipods have the best music quality? Better Usability? More features? Now with more than few days with each one of them I can help with some answers.
Music/Audio Quality :
They are all the same in terms of Audio Quality.Also the headphones given with all the three ipods are exactly the same and they all sound bad. So get some good headsets from sony,Sennheiser or the Bose.
If you are someone looking for features then ipod touch will win undoubtedly in all the features other than what you typically expect from a Music player. Ipod touch allows you to check mail,Watch youtube videos and browse internet and lets you use your ipod just like a Mini laptop (Given that you have access to wi-fi), all these features are very relevant to us customers. But many of them become totally irrelevant say to customers in india (thanks to lack of wi-fi in 99% of places).
Same goes with the Video feature, though videos can be fun with Ipod Touch, but watching a full movie will drain your battery (same goes with Ipod Classic and Nano too).
The battery performance of apple Ipod Touch and Ipod classic is much better than the Nano, the Nano's battery in a normal usage would'nt even last for 6-7 hours for music, if you keep playing with it. The other two are far better in this regard.
The Ipod touch is the best in terms of usage, the scrolling of long lists and spotting songs is best in the Ipod Touch. Both the Nano and Classic lag behind. After using the Touch I felt crippled with the Ipod Nano.
But the Nano makes up for its shortcoming with its small size, very easy to carry in your pocket, which is practically not possible with the touch or Classic. Inspite of all the extra features I felt more comfortable with the Nano just because of this reason.
Final Choice :
This is definitely upto the individual choice, if you want a highly portable device then Nano is the best. Want more storage than 16/32 GB then the classic is the option. If you want to carry around and play with more features like browsing/youtube then go for Ipod Touch.