Definitely a house.
A car has the same downsides as a house, plus more downsides, and none of the benefits of a house. A car requires more and more maintenance over time, you have to pay taxes on it, it depreciates in value, eventually it's not driveable, it can be stolen, it can be wrecked, it can be towed, you constantly need money to operate it (gas and insurance), you never have any security or stability with it, and eventually your health is going to go which will make having a car impossible.
By the time my home is paid off, I'll probably owe $200 a month in property taxes but by that time I could easily get $1000 or more a month renting out a room to a person or $2000 or more a month renting a room on Airbnb. Plus my home has appreciated in value and I have security, stability, safety, community, a place to recuperate when I'm sick and rest un-bothered when I'm tired, etc.
I really liked traveling in my car and I'm hoping to love living out of my SUV for years to come but vanlife, by it's very nature, is not permanent. Even Bob says eventually he'll be old and need to be in someone's RV or mobile home in one location.