I tried Shadow and, well, you could really tell they host in a budget datacenter with how often there was stutter or missing keyframes (they host with OVH in Europe). I never had such issues with GeForce Now.

Also, I found it kind of scummy how they will not actually tell you what hardware you'll be getting beyond "4c/8t". Mine turned out to be a low-clocked Haswell, a CPU so outdated that Steam downloads were CPU throttled. I used it for about an afternoon and then immediately cancelled.