The optimal gas insert is a direct vent insert. It is completely sealed from the indoors so it does not affect indoor air quality. It is safe, even for sleeping rooms -- some gas logs are not. And it is highly energy efficient. Most traditional fireplaces, whether insert or not, send most of the heat up the chimney, so they do not heat much. Direct vent throws off really serious heat. But they do cost -- prepare to spend $2-3K.

Wood inserts are typically not direct vent, which means they are not sealed systems. But I believe they do provide more heat than a conventional fireplace. The advantage of the gas insert is that it requires little or no attention, especially if you get one with a remote thermostat. But if you like the idea of lighting a fire and keeping it going, wood might be right for you. In that case you should take a look at the forum in >. The guys there love wood and are happy to be helpful.

Whatever you decide, make sure you check out the background of your installer. These devices take at least a whole day to install properly, and you need someone who will pay attention to the details and get them right.

For some reason, the website I mentioned did not get printed in my previous post. Here it is:

hearth.com