In the US, I’ve used rental limos on several occasions, including ExecuCar and BlackLane. They’ve both been great — not a single bad experience there. But there’s a huge leap downward from that to the “black car” service from companies like Uber.
I’ve had occasion to use regular car service from Uber and Lyft, and between the two I think Lyft is better to their drivers and their customers. But that’s like saying one pile of poo is better than another pile of poo, because it stinks less.
I haven’t had any really horrible experiences from either Lyft or Uber, and I have had some really good ones. But it’s a lot more hit and miss. I think they might be better than your average taxi, but only in some places. In others, I suspect your average taxi will still be better.
I do prefer to use local co-op transportation services instead of either Uber or Lyft — like RideAustin here in Austin, TX. I’ll use RideAustin over Lyft or Uber any day of the week.