At our NACD evaluation, Bob Doman recommended these foam non-beanbag chairs made by a company called LoveSac (officially the worst company name of all time). He thought it would enable us to keep Collin more upright without strapping him in like so many of the seating systems do. It would give us infinite incline possibilities while allowing Collin freedom of movement and helping him hold his head in midline, which he detests when it's up to him. We checked into the options and ended up ordering the CitySac so he would be able to use it for a long time and yet it wouldn't swallow our house like some of the bigger options might. Here he is enjoying it after some therapy. (That's how his father likes to bundle him up. Cute, but totally unnecessary.)
He seems to like it.