My current setup is IKEA coffee table on top of desk, as shown in The Standesk 2200
Standing allows me to move freely and if I need to move to get something, I don’t have to “get up” from my chair.
I’ve always found sitting in a chair uncomfortable afer a while and have considered getting better chairs. I’ve used an exercise ball as a chair for a while and it is an improvement over a regular chair.
Then I had the insight that getting rid of sitting altogether is a more elegant solution.