I spend 10-12hours/day looking at a screen...
Bought one of those fancy-dancy Raynor Ergohuman chairs to replace an Aeron a few years back. It lasted about 14 months. Much more comfortable than the Aeron, but made for ****. Went to an elevated, standing desk by a different company (not varidesk). That experiment lasted about a month and it was a struggle to make it that long. Pain in the ***. Good idea if you have the freedom to move around occasionally, but if you're chained to a desk, you;ll hate having to stand. Well, I did. And switching back and forth, up and down, was nothing short of wasted time and an effort in frustration. You stand so long you want to sit, then you sit for 15 minutes and feel guilty that you dumped a grand on a ****** standing desk, so you stand up. Meh.
I now use a unipivot stool and footrest with an elevated desk. Best setup yet; leaning. F_uck standing all day. You can have those last 5 years of life. I'm sitting.