Never heard of houfy, but have friends who rent their place on VRBO. They have been very pleased with how it all works. With any of these rental websites, the main thing if you are renting is to see how many places there are to choose from so there is price competition and you have choices. If you are an owner, listing your place on a large website means more people will have a chance to find your place. I am sure a lot of copycat websites will pop-up since it seems like an easy way to make $$$ if you run the site and there isn't anything unique about how it works.
You can probably check the legal wording on their website to see what type of protection that offer for renters. I know the VRBO handles that very well.