Vent free fireplace

I am sure this has likely been covered in the future we plan to build a new house and I was wondering about a gas fireplace. I just want one for emergency power outages in the winter. I was wondering if a vent free fireplace would be okay for this since I have read article that they aren't that safe. So was wondering if I should go with a vent free or pay more and have a vented gas fireplace. Again all I would use it for is if power went out to keep the house warm. That is pretty rare for that to happen here unless we have an ice storm

I was wondering what other people experiences with a vent free fireplace was like. Like I said I read they aren't that safe on some sites and you need to keep the clean for them to work right.