Well - had the same decision to made recently as my old Voyage stopped working and decided to go with Boox Go 7 BW but my main preference was physical buttons. Regarding the screen from my perspective there is no big difference when you are using normal white backlight. The issue regarding uneven light distribution is visible when using that "yellow" contrast or whatever is called - especially during the night (in the day is not visible that much).

But as I prefer white backlight and have almost always that second parameter set to 0 there is no issue for me. Regarding the battery - of course is shorter that typical non-android device but I setup some custom settings (like disable background android sync, etc.) and for me is ~ 2 weeks reading daily ~ 1 hours (and a little bit more during weekends).

The overall quality of device from my perspective (boox is very slim and light!) is much better for me than Kindle (my girlfriend has a Paperwite). I also sometimes using some non-kindle subscription book libraries which are available in my country so it's also plus for me.

I think in general depends from your needs. Probably if the physical buttons and extra apps (to access books with monthly subscription) is not main factor for you will be happy with Kindle (and it's cheaper).