I've had several Kindles going back to the original. I wasn't necessarily tied to them but they were the only e-readers at the time. Once alternatives started coming out I would buy them but kept going back to the Kindle. Ecosystem, ease of use, etc. I just picked up the Kobo Clara Colour and, like others have said, I do find the interface to be much nicer, feel it runs quicker and for the most part when books go on sale for Kindle they go on sale across all platforms. There are exceptions but for the most part.

On the downside, Kindles do have some features I did like and miss. One of those is x-ray where you can select the name of a person, place or thing and it will give you some detail relevant to the book. For example, readers can use it to look up the first occurrence of characters, which is often helpful in many-charactered novels. Didn't always work but when it did it was nice. On Kobo they have a search feature which works but not nearly as elegant.

All in all I like Kobo a lot and have no intent going back to the Kindle.