I wouldn't want to do either one all day long but if I had to pick, I'd choose sitting down. Standing all day would make me incredibly tired and I'd want to sit down. If I'm tired of sitting and want to stand, I can atleast stretch my legs out.
I would much rather sit all day than stand all day. I couldn't imagine standing all day. My feet and back would be killing me if I were to stand all day.
I'd prefer to do both. I usually sit all day on the computer anyways, and it's really unhealthy. I'm usually standing all day at work anyways, so I've experienced both. I feel like a mix of both is the best!
I'd much rather sit all day, because when I stand just for 2-3 hours in a day my legs get tired and I must sit down somewhere. But sitting all day is hard too, if it wasn't a choice for just one of these I would pick the combination of them both.
I'd definitely much rather sit all day, even though it sounds really unhealthy. I'd be up for standing all day too, but I think I'd get tired of that a lot easier.