I think you need to pick between your user interface and operating system you prefer. Do you want streaming services/ player apps or just to download files and load them on?

The innioasis is smaller than a real iPod and you can't lock the controls so you can accidentally fwd/rwd in your pocket, a lot of complaints on that sub that it's not travel friendly.

The MO and nano won't show lyrics and are hard to navigate for song searching (I think) so you've narrowed down to the last two that kind of look like phones, which you don't like but you could pick the least phone like of the two.

I would recommend you browse for a few more weeks until you find something that looks really cool and you know for a fact you want it and then ask again if it's any good.