I’ve had a Chair One for six months or so, but I’ve not tried a Ground, so all I can tell you really is that the Chair One’s really nicely put together, goes up super easily and is stable and comfortable. I don’t really find I use it much on muddy ground, but I guess if that’s a consideration for you, the Ground might make sense due to the increased base contact. There’s a YouTube video of someone comparing the two if you’ve not seen it:
[video]https://www.youtube.com/watch?v=wOo6dEOgEnk[/video]
Looks quite a lot lower. Anyway, really nice kit where space counts. Great in an overloaded car or camper van etc.
ps: avoid the Therm-a-Rest Trelo thing, it’s really unstable, reach for a glass on the ground next to you and next thing you know you’re lying next to it 🙁