I don't have any real advice, but here's [1] the one I got, which has been good for me. And it looks like the price has come down a good bit since I bought it in early 2015.

[1] https://www.amazon.com/gp/product/B005UA2WO2/ref=oh_aui_deta...

I've been using the Topo by ErgoDriven. I like it, but at the same time, I'd like to try something that isn't as soft. I should add that I prefer to be barefoot whenever possible and when I'm not I'm usually wearing shoes that don't have any support or much cushioning. I can't think of a natural surface that I've been on barefoot that is remotely as spongy as the Topo.

At work I've used an Imprint CumulusPRO mat and it was very comfortable and took a lot of abuse like using my chair on top of it half the time.

i would definitely recommend an anti-fatigue mat if you're using a standing desk. our mats are sold at $39 to compliment our SmartDesk.

https://www.autonomous.ai/anti-fatigue-mat-standing-desk-acc...

Your site doesn't display on iPhone, most probably you have an overlay darker gray pop-up that blocks from viewing anything on the site. I can see just the outline of something in background

Rubber lower mat: Genuine Joe Anti Fatigue Mat, and a foam upper: Imprint Cumulus9 Kitchen Mat Nantucket Series

How does a mat help? O__o