The Kurzweil K2000. I love the damn thing.
I first saw one used around 2001 or 2002 I think. I had such LUST for it. I didn't have the money, though. Finally in 2004, I joined eBay just so I could hunt one down, and got a basic unit. I loved it so much, I sold it to buy a K2661, thinking it would be better. Nope. Mistake. Just didn't connect with it. Got another in 2020. It broke in 2021, and I got a K2vx. I love it so much. I'm probably just a weirdo, but something about it's limitations I find magical.