Either propane or charcoal could do the job properly. The advantage of charcoal is that the grills are more portable than a gas grill of similar surface area. The fuel is easier to carry around as well. It reaches a higher temperature using lump charcoal. It is however messy and requires getting rid of ashes, requires more tending, and requires more effort for consistent results. 
Propane would have the opposite properties. As for me I've used both and was a long time hold out for gas, but time is often an issue for me and not having to fuss means I grill more with what I have now. My particular grill can reach 650F which is as much as I need. 
What I've learned is that charcoal does not produce a better flavor than propane. The difference is in the design and use of the grills. 
Charcoal is inherently "smoky" but all smoke isn't equal. Any which is given off before food is laid on the grill grates is from incomplete combustion and as tasty as car exhaust. Once the coals are glowing hot however the juices dripping from the food produce smoke which is what people are really after. Years ago most gas grills didn't have a design that takes advantage of this and were virtually "smokeless" and that did leave them at a disadvantage. Nowadays there are "flavorizer bars" or some such terminologies, but they are simply burner shields or something similar which is heated by flame for the juices to fall and that produces the same smoke that charcoal does. 
The end result is that properly constructed and used both provide good taste. It's the person who's doing the cooking which ultimately determines quality.