There have been some really significant improvements in small "space heaters," as these are called; but since the advertising department where they make crap can use the same words as the guys who build the good stuff, it can be really difficult to find the differences.
The point can be stretched to say that whatever (electrical) power goes into a device and is "used" eventually comes out as heat. This allows the ad guys associated with the lesser units to say "they're all the same capacity."
Your problem is NOT just to "heat the room." What you really want to do is make the room comfortable for people who are in it (and maybe to keep a few things from freezing up).
Any unit with a fan is attempting to heat the air in the room. This may be a necessary part of making things comfy, but it's actually more efficient to use a unit that produces a significant part of its output as "long-wave radiant" output. This heats the objects in the room - including people - directly, so the objects/people are warmed without the intermediate heating up of all the air. The air will eventually pick up heat from whatever is warmed directly, but in the meantime you'll feel comfortable at a lower air temp.
If you only heat the air, the air has to be warmer than objects in the room to pass any heat to the furniture (and the people). If you heat the furniture and the people, the air can remain at a lower temp and you're still comfortable.
If you intend to heat the area continuously, and always maintain the same temperature, it doesn't make a lot of difference what heating method you use, since once the temperature is established the amount of additional heat you need is determined entirely by how much "leaks out." If you only turn on the heat when you enter, and shut it off when you leave, a "radiant heater" of some sort is likely to be less expensive to operate. Most good "ceramic heaters" are intended to produce lots of infrared output, but cheaper ones just have a "ceramic element that gets hot." Whether or not it has a fan probably won't make a lot of difference.