This is just my anecdotal experience, but most of the time when I compare Waymo and Uber prices in my city, Waymo is cheaper.
For example, I’ll use both apps to calculate the fare to the same destination. Waymo is almost always slightly cheaper, and that’s before considering that you aren’t expected to tip.
Even if it was slightly more expensive, I’d prefer Waymo every time. Not having to deal with a driver, being able to put my own music on, and the flexibility of being able to edit my route at any time are great.