I think Cruise/GM is winning. Waymo has distance, cruise/gm has velocity and acceleration. Retrofitting pacificas is not scalable. You basically have to be or buy a car company to actually deploy a profitable self driving taas at scale (and it still won't be profitable overnight) imo, and that will be true until you can buy self driving cars directly from manufacturers, which will probably happen like ~2 years minimum after the first car manufacturer starts deploying their self driving taas.

Why is this? Because self driving cars require shit tons of wiring (and quality wiring at that) and redundancy, and you want to do that in a plant, not by hand; moreover you can save a lot of capital costs by making your taas car more like a model 3, that is, stripping everything out of it, but you can't get those savings by just retrofitting pacificas. Google isn't playing to win at this point - maybe they don't yet believe it's ready for deployment any time soon. Personally I think there will be (perhaps somewhat small) geofenced publicly available commercial deployments within 2 years though.

Also I would rank tesla dead last, less sensor capability than everyone who's trying it seriously (this impacts data collection ability)... model 3 is a botched attempt a self driving taxi, serious financial issues, there's been a lot of turnover in their self driving team with people leaving for places like argo ai (self driving startup ford bought), and, ideologically, they can only deploy electric self driving cars without hurting their brand (though all self driving cars will be at least hybrids).