If you don’t consider the sound quality, then consider the appearance, operability, and song management software.
1 Appearance: Personally, I feel good except for the nano5 (very ugly). (After the launch of nano5, IPod sales dropped. It seems that everyone feels the same way). The iPod's market share in Europe and the United States has reached 70%, leading to an increase in the crime rate of theft and robbery in Europe. It shows that everyone quite recognizes its appearance.
Iriver is not bad either, quite generous and quite simple. Just a bit thick.
2 Operability: This is Apple’s specialty (various shortcut keys and mouse functions in Mac OS, Iphone’s multi-touch, Ipod’s circle... Moreover, it is still not available now) Stop registering new patents in IO, Apple depends on it)
Iriver (operation) is the worst I have ever used (I have t7 and E100).
The buttons of t7 are too hard, and the keys of E100 are too loose. And the response when changing songs is slow. Don't know if the E150 has improved.
3 Management software. Personally, I think iTunes gt; plus 3 and plus 3 are not very compatible with Windows 7. However, iTunes sometimes conflicts with other video software that has qiutetime decoders (such as Video Storm), so be careful when installing.
4 Others Due to copyright issues, iPod must be worn through software, and iriver is more free. But you can solve this problem with Floola.
Another: If you don’t consider sound quality, there is absolutely no need to buy Iriver. Besides, they are both famous brands and portable devices, so the difference in sound quality is not big. (The reason why I bought iriver: the sound is indeed better, and more importantly, the noise control can be described as "amazing". I usually use UM2, Xiaomi 4, and 10pro, so I am more sensitive to this problem.)
Conclusion: Stick to iPod. If money is not very tight, stick to iPod touch. It has many games and software, and it can also surf the Internet. It will be even better after jailbreaking.