How big of a space/how well insulated?
I heated my shop (30x40 w/ 10' walls, very well insulated) with all of the following, but not at the same time - 2 burner tank top propane, 3 burner tank top propane, a 75,000BTU torpedo heater, and one of the radiant kerosene heaters that looks like a round metal can with a wire cage around it.
By far the torpedo heater worked the best but the fumes will kill you. I think it actually made me somewhat allergic to diesel exhaust. I ran offroad diesel, road fuel and clear kerosene in it... all were really bad. I can't be around one of those or a diesel truck now, the fumes make me cough so bad that I gag.
The 3 burner tank top heater is my second choice, those things are legit and put out a lot of heat but you need a 40/50/100lb propane tank. It'll freeze up 20lb'ers if you have all 3 burners on high. It would keep my shop at 60-70 degrees easily on cold days. The fumes are noticeable but tolerable. My main complaint is that burning propane puts a lot of humidity in the air and my tools would get rusty.
2 burner tank top was OK, it would take the chill off in that space but it wasn't really "heat".
The radiant heater is nice. Honestly I love that thing, it burns really clean and there is not much smell. The heat is almost like a wood stove. It doesn't put out a lot of heat though so I mainly just keep it as a backup in the house if the power goes out and I have 15 gallons of clear kero on hand. Kerosene is $$$$pendy!!! You also shouldn't run died kero or offroad diesel in these as it will contaminate the wick.
Now I've got an 80K BTU natural gas heater in the shop so unless the power goes out, I'm really frickin toasty and it costs almost nothing to run it.