My take on propane is that it is safe when you used it based on the manufacturer’s instruction and you have proper ventilation in your house. Check out Mr. Heater Buddy’s propane, they’re the most reputable brand when talking about prepping.
I think it depends on your situation. I use electric space heaters for my small apartment and it works well for me – no complaints whatsoever, cheaper, cost-effective, no wasted energy.