Honestly just a basic, very comfortable recliner with a lap desk. I'd say 70-80% of the time I'm at my standing desk though...and only use the recliner for when I won't need the keyboard too much because as you say the lap desk isn't that great. I leave the mouse on the recliner arm (it's wooden).

It works for me. Back pain went away in about a week.

Standing desks take some getting used to but they don't cause back pain for me. Only sitting does (prob my posture or something but oh well)