Echoing what AlaskaProf said, the Wallas diesel units are really, really nice. They have a ceramic cooktop, are quick, easy and safe to use, and can provide wonderful, dry heat for the cabin as well.
We have a traditional diesel cookstove which is fabulous, but it takes a while to warm up and always dumps a lot of heat into the boat, which isn't welcome in the warmer months. It is the warmest, driest heat ever, though, the standard galley stove of almost every fishing boat in the Pacific Northwest, western Canada and Alaska. Hereabouts, the wisdom is to light the diesel stove in September, and run it continuously through May.
Propane? It's as safe as the installation and owner. People all over the world use it, just like they do gasoline engines. The technology to do so safely is utterly simple. Downsides? Besides the special concern about propane's density when it escapes its tank, it releases tons of moisture into your boat, a product of combustion. We use a propane grill and single-burner stove outdoors, both mounted on our cockpit railing, our primary cooking spot in the summer. The previous owner had a butane burner for making coffee during the summer.
Electricity? I simply cannot relate on a pleasure boat. Sorry. I grew up cursing the thoughtless folks running loud gensets all evening in quiet anchorages, and just can't go to the dark side. Yeah, I know they're much quieter now. I won't cook on electricity at home and see no reason to on the boat, either. Microwaves? No thanks. Converting liquid or gaseous fuel to electricity to run a microwave makes no sense to me when the original fuel could heat the water/food much more simply, reliably and efficiently.
Alcohol? Had it on a Yankee 38 and absolutely hate the smell and anemic heat it generates. Yes, the modern Origo is far superior to the pressurized stoves, but it's a stupid fuel when one compares it to the alternatives. I feel the same about kerosene, which I had on my Bristol Channel Cutter for both cooking and heat. Never again.