In fairness, I have not had a chance to try Stadia yet; I'm waiting for it to become available on Chrome without needing to buy the Premiere bundle. Until then, I have no practical use-case for it, as anywhere I can plug in a Chromecast to play it I could just plug in the actual hardware to run the game locally or do Steam streaming. Playing AAA games on my lunch break at work, which I've been doing with GeForce Now, is pretty cool.
That said, I can't say I've really had any issues with GeForce Now's image quality on my end, which is actually surprising because I've been having intermittent network issues the past couple of months at home that are throttling down my speeds to the 30-40 Mbps range. I get occasional lag or hiccups, but it's usually only a couple times an hour, and I can't rule out it just my network being kinda shit at the moment.
I get the PC stuff, but it doesn't bother me too much; though I would say I'm a "PC guy" so that's probably not too surprising. My complaint there is I just wish it was more consistent: sometimes games launch pretty seamlessly, sometimes they need to update, sometimes a literal Steam instance opens up and I have to wait for the game to "download", though it does that in only a couple minutes even if the game is hundreds of gigs in size.
My biggest complaint about Stadia, especially now comparing these two options, is that Stadia games are exactly that: Stadia games. I can play it on Stadia, or I can't play it. GeForce Now is just an additional option added on to the many ways I access my one copy of my Steam game. I can download it locally and play it on my gaming PC, I can stream it via Steam Remote Play from said gaming PC to my TV or phone, and now when my wife needs to use desktop for work, I can stream the same game off of Nvidia's servers without my PC entirely.
I think there's absolutely a niche for Stadia. Folks who want that, as you said, console-like experience in a streaming service and folks who want the upmost graphical fidelity (unless Nvidia rolls out more tiers/options down the line) might find Stadia really works for them, and that's great! But I just don't know if being niche is going to be enough when the dust settles. We'll see, I still hope to try it out at some point and decide for myself.
