convection > torpedo by a longshot.
Torpedoes are nice if you’re working in one narrow area. They are also sooty, and noisy.
Convection will heat up an area of ~15’+ in diameter (a 2.5 car garage), will not smell, and is relatively quiet.
My only problem with any of these is that they produce moisture which hangs in the garage and on the surfaces (tools, body parts, blah blah blah) because the combustion exhaust is not vented outside.
Modine hawt dog (w/vent) FTW. But thats not portable.