My first Kindle was the Kindle 2i. The "i" meaning "international" which meant it connected to UK 3G networks etc. But you had to buy books out of amazon.com as amazon.co.uk had not Kindle store. I got this in Nov 2009.
If I'm honest I liked it as a gadget but I never really loved it for reading and didn't use it much.
Then in Aug 2010 I got what is now called a Kindle Keyboard and it was a game changer because the screen was so much better. I got it with the leather cover which was one of the best on any device. That kindle has a lot of sentimental value for me.
At some point my dad expressed an interest and so I donated it to him as an excuse to upgrade. He kept it and used it for a number of years. At one point I tried to upgrade him to a new PW 3, because he wanted one with a light, but we discovered a problem. My dad had macular degeneration by then and he used the Kindle on maximum font size. We found out that maximum font on the PW was smaller than max font on the Keyboard. So he kept the Keyboard and used an external light.
When he passed away I got it back, and it still works, although because he kept it in a drawer for the last year or so of his life the battery is almost shot. But it's working, it's jailbroken and with Koreader on it. Not that I use it much. I basically fire it up every so often just to keep the battery alive. But even if/when it eventually dies I'll keep it because it's "Dad's kindle"
After that I got a Kobo Touch. Another game-changer because of touch screen.
After that for several years I was alternating buying the latest Kobo and Kindle. But also a couple of other devices like a Cervantes BQ. I actually kept most of these. I called myself a collector rather than a hoarder to make it seem ok.
Last new device I bought was a Kobo Libra Color because I wanted to see what colour eink was like. My ereader buying habit faded because I've been reading less. But that may change again.
I may use the 20% discount to buy a new Kindle although none of the current devices really tempt me.