Unless you count things like “on top of stalagmites” as sitting methods.
From Blackadder:
Aunt: ‘Chair’? You have chairs in your house? Edmund: Oh, yes. Aunt: [slaps him twice] Wicked child!!! Chairs are an invention of Satan! In our house, Nathaniel sits on a spike! Edmund: …and yourself...? Aunt: I sit on Nathaniel—two spikes would be an extravagance.
For me, sitting in seiza is more comfortable for the upper body (compared to sitting cross-legged), but less comfortable for the lower body. The latter has been less of an issue as I’ve had more practice.
Seiza has got to be one of the least comfortable possible ways to sit. Unless you count things like “on top of stalagmites” as sitting methods.
From Blackadder:
Aunt: ‘Chair’? You have chairs in your house?
Edmund: Oh, yes.
Aunt: [slaps him twice] Wicked child!!! Chairs are an invention of Satan! In our house, Nathaniel sits on a spike!
Edmund: …and yourself...?
Aunt: I sit on Nathaniel—two spikes would be an extravagance.
I think I smell a generalization...
For me, sitting in seiza is more comfortable for the upper body (compared to sitting cross-legged), but less comfortable for the lower body. The latter has been less of an issue as I’ve had more practice.