The nest hello itself is a better, smarter camera but I don’t know that it’s that much better as a doorbell, particularly when you take cost and integrations into account. The ring starts out about $100 cheaper and is also less expensive for the annual plans. And the ring comes in a battery operated version for people who need that. And ring just has more integrations available, including with smartthings and IFTTT and of course much better integration with echo. (Be careful when reading about integrations: the nest doorbell does not yet have the same integrations as the nest cameras do.) And most of the independent review sites, including consumer reports which does lab testing, say that the ring response time and the Nest response time are about the same.
Choice is good, and if the camera quality on the ring really bugs you, you may indeed be happier with the nest or one of the other video doorbells.
We have several of the small echo shows in places like the laundry room and we have a ring doorbell and we really like being able to just say, even if you’ve got your hands full of laundry, “Echo, show me the front door” when the doorbell rings. That handsfree option is not available with the “nest hello” on any device as far as I know, although maybe it works for the one of the google nest homes with a screen. (Those are all much more expensive than the echo show 5, though.)
As far as Echo versus Google, lots of conversation about that in the forums, and as @nathancu said, The two companies keep leapfrogging each other in terms of features.
If you’re already all in on android and Chromecast you may like the Google better. Certainly if you want something that can answer complex homework type questions.
At our house, we have one Google home but we all prefer the echo. Right now it does much more in terms of home automation and the far Field voice recognition is better from across the room. And we use a lot of the features that are not yet available on Google. but both are good systems.
If you like the nest cameras better, you’re willing to spend more money, and you don’t need as many integrations, go for it. There’s certainly no reason to stick with a system that you don’t like, there are many options available.