Around here the folks who can afford them get the vented style propane heaters. It is nice to wake up from a nap alive.
Sunflower heaters work nice, but they produce carbon monoxide. If your shack is sealed up tight you need to address the ventilation issue. In my oppinion, a buddy heater may be on the small side for your shack. A big buddy may be better suited to your needs. I personally like the buddy heaters because of the low oxy shutoff and they shut off if you tip them too.
People think that carbon monoxide smells like like truck exhaust and it burns your eyes, this is not true! CO is a silent killer with no smell or taste.