Here is some anecdata: Last two home sales I did were 1. FSBO and 2. to OpenDoor.
FSBO was kind of a pain because, after they looked at the home, the buyers brought in their "agent" who was also their aunt. We agreed to pay her a flat fee commission and for this she was supposed to handle all of the paperwork, lockbox it after we moved out to set up the inspections, etc. She was technically licensed but was very, very unskilled at her job. She didn't even have a lockbox, for example, and then she bought one online and had it mailed to the home address where no one was living. She also didn't seem to know how to fill out the boilerplate forms, so we ended up correcting all of that based upon our own experiences with it previously. They were unrealistic first time home buyers, and it was a small, older home, not a brand new home, and that's a dangerous combination for a drawn out process and unrealistic requests. In the end, between our own contract and business experience and a good closing lawyer, the deal got done fine, but the agent was worse than worthless. If I had to do FSBO again, I would not agree to work with a Buyer's agent unless they were very experienced with a lot of transactions under their belt.
OpenDoor was a breeze. I had a very thorough knowledge of the home prices in my area since looking at houses is a bit of a hobby of mine, and I wanted a quick sale since I was using the proceeds to buy another home. No time for flaky buyers or things falling through! OpenDoor did an inspection and measured the spaces, but they did not ask me to repair a single thing, which I think this is their new model. They even raised the offer a little bit after I responded with information about new roofing and siding. OpenDoor closed with me in less than 3 weeks, turned it around in a couple months and made about $15K (minus minor repairs) on my 300K home. There were no surprises.
Zillow, on the other hand, gave me an initially higher purchase quote, but then they came up with a crazy list of repairs, so I laughed in their face and sold to OpenDoor. Then they called me over and over. Thumbs down to Zillow. There was a third "we'll pay cash your home" company in my area that was really just realtors trying to get you to list with them; they never managed to come up with an offer other than offering to list it for me.
Good luck with your sale!