As you consider choices, be aware that ventless actually vent out into your home. Some feel this is a significant health risk.

If there is one subject that there are a lot of opinions on, it is this one.

We always recommend a direct vent gas fireplace where possible. The unvented models, although essentially 100% efficient, cause indoor air quality issues primarily due to excessive water vapor, not carbon dioxide as some think (which is harmless), not carbon monoxide (because the CO produced is minimal, less than 15 ppm). Also, an improperly installed model can cause sooting problems.

The other issues are associated with odors. Since unvented fireplaces use room air for combustion, anything in that room air, including off-gassing carpet formaldehyde, new paint, chemical air fresheners or household cleaners will change the smell in the room when those chemicals go through the burner. The worst case scenario is probably a new home, where the air is full of chemicals from off-gassing.

Some folks are more sensitive to smells than others or have other respiratory issues. We strongly recommend against an unvented fireplace with those folks.

The only downside that I hear complaints about with direct vents is that all have sealed glass fronts. The good news is that there are some tricks to making the glass disappear, such as in the photo below.

Maybe this bump will get more folks to chime in with their experience.

We have a vented gas fireplace in the living room, with a blower added, and an unvented one in our bedroom. Because it is unvented, it is much smaller unit. I hated the fake logs and replaced it with recycled glass made for that purpose.

We have a ventless gas fireplace that we put in our basement to add warmth in the Midwest winters. We LOVE it! It pumps out a ton of heat and heats up the basement quickly. The "smells" that people are discussing are not an issue for us. The only smell it gives off is the same gas smell you get from your gas burners on your stove.

The only experience i have is this, my friend lived in old apartment and it had an old stove/oven. One side of it was made specifically (from manufacturer) to heat up the small apartment. No smells and no other problems but her apartment was not well insulated so there was always good deal of make up air. In newer constructions where insulation is key i worry about make up air (oxygen level not being replenish)