Hello there,
If you want long term stability in the operating system, both of them are pretty much equal but iOS will be superior.

Huawei's EMUI still has a lot of work to fix on, there just isn't much of the stability on it.
I believe that since you mention iPhone 7 you should be able to afford it, go for the new iPhone if you are willing to pull out the extra buck.
Although keep in mind that there is no 3.5mm headphone jack but it comes with a converter from 3.5mm to lightning. So music listening shouldn't be much of a problem here.

Tell us about what kind of stuff you are looking for. It could be you're a user who's concern with security patches and wants by far the safest OS or you just like big screen with pen so you can have easy usability.

Thank you.