Kenwood HDD-based players are also very good.
And ipod 5g just sucks when listening through headphone out. I don't know, maybe switching to a line-out (+amp) and imodding the ipod will help, but you should specify that.
If you don't care about money I give you the final recommend, which are called "four magic": sony d50, iMOD, kenwood d9, B&O 2 as ufo in common. They have the best sound as MP3 player, and their prices are also fantastic haha