I've had the REI version of the Helinox for years, never found a comfortable glassing position. You just end up fighting the natural recline of the chair trying to sit up straight in it.
If you have level ground (sometimes it's worth the effort to level it yourself if you're going to be glassing for awhile), the little Helinox Zero is nice—definitely nice at camp!
It seems like the vast majority of glassing is done on a slope where a good pad and my pack works better
I am a Crazy Creek Hex 2.0 fan. Adjustability is awesome, rolls up to be not much bigger than what a glassing pad would be and it's good in uneven terrain.
I used a Crazy Creek style for years (lightweight no longer made Osprey, it was great but it finally wore out). Several friends use Crazy Creek's. Hillsound stools work well and there are many fans of them out here. I have one too and it works great but it's mostly used at the truck. I have gone back to basics (light) and just use a pad to sit on. Not glassing but early CO elk I pack a Helinox. The only place the Helinox works glassing is flat/flatish ground with my big tripod that can straddle the chair.