I bought one called "Zipro New Lite", but it seems to me this one, along with many others, are just "brand" variations from the same chinese manufacturer. No regrets, happy with it, has an app (fitshow) integration with myfitness pal and google health. It has a display for number of steps, calories, duration, etc. on the board itself so you don't even need the app. The only thing I keep track of are steps. Trying to hit at least 8-10k a day.

I had one briefly but I think it's important to think through the logistics of using it. Even the small ones are somewhat heavy and cumbersome. I ended up returning mine because it was too much of a pain to set something up and tear it down just to get steps in. Maybe different if one has a dedicated place for it.

I just bought a WalkingPad M2 and my first day on it was yesterday. I usually sit on my couch while working. I walked about 6 miles yesterday instead! I woke up with sore calves and I think I'm getting blisters but these are probably good signs.

at work there is a small conference room with a unSit. Not small - it is shorter, but also wider. I like it and often reserve that room for an hour to get some steps in. However I've never tried any others and so I can't say if I'd be unhappy with the others. I did find a free craiglist treadmill a few years ago, but the setup I had with it meant I was rarely using it.

I don't think I could stand/walk at a desk all day, but I still want one because I could easily do several 1 hour blocks during a day and it would be better. However some ability to get a chair seems important if it is at your only desk.

I bought the DeerRun Q2 last year and like it, although the pad itself is small so it’s only good for somewhat shorter people.