I loved my Jambo when I had it. Jambo and Lang aren't in the same league build quality wise. Insulated firebox is standard on little Jambo. As far as options, you would want the 3rd upper rack on the side closest to the stack and casters to move it(those might be standard). I've never seen a Horizon or a Gator up close so I can't comment on those.
Smoke Bros BBQ Springfield, IL. 2 Gateway drums, 22.5" WSM and kettle, C-G Akorn