For my daily drivers I have a pair of Kinesis Advantage 2's, purchased in 2007, still kicking.
A couple of years ago I hit up their email support with what I thought was a stuck key. They (correctly) diagnosed it as a failing switch, helped me identify another that was failing, they figured out that I'm handy with a soldering iron, and mailed me a handful of new switches and other swag free of charge.
$370/ea 18 years ago, and I'm pretty sure they MSRP for the same price today.
Nearly all of the labels have worn off of the keys. I never mounted the fabric palm pads, and the plastic palm areas are now mirror polished from use. I also modded them both with a Thinkpad style nub mouse.
Things I'd change, but given I'm pretty good at modding and haven't done them they are relatively minor:
- Less clicky switches for the one I take to work. I already tend to pound the keys, and I make a noticable racket on the rare occasions I'm in the office.
- USB-C connections, including PD on the built in hub
- Qi2 wireless charging in the blank gap in the middle
- A smarter programmable controller like the the nice!nanos on my corne
I'm seriously considering a DataHand-like keeb like the Svalboard