I have a Kobo and my wife has a Kindle - I like the Kobo way better, primarily because the Kindle is trying to sell me stuff all the time.

It's likely because kobo's can be flashed with a custom OS https://inkbox.ddns.net/, which can sync with https://calibre-ebook.com/

I have a kobo as well and I I did a lot of research before selecting it. Imho it's the best on the market for my personal needs and that definitely changed how often I use it vs an alternative. Some of the things I like about it are direct integration with the library and the ability to do audiobooks. I also like that it is only an ereader and I can't play games or surf the web on it. I think knowing what's gonna help you as an individual is the most important thing. If you're more likely to take a fully fledged tablet with you somewhere because of the versatility, and would otherwise leave a plain ereader at home, then a tablet is better because if you decide to read at least you have it with you. Like a lot of tech, I think it really depends on the user.

For me it's the ability to read outside in bright days, so I can take care of kids in the beach/pool.

I went for a boox since it's an Android and can run not only my favorite e reader app but also dictionary, browser for Wikipedia, and any apps for Android such as news Guardian, DW etc.

Obviously it also runs official apps such as Kobo, kindle etc, so I can try/ buy the book wherever and later I de DRM it and upload epub.

Oh also I have severe dust allergy from physical books, and moved countries a couple times leaving behind lots of unread stuff.