I went with Fire Stick when I cut the cord. Later I bought my father a new TV to stop him from buying yet another bulb for an ancient DLP set. The new TV had Roku built-in so I became familiar while setting up the TV and cutting his cord.
I found I preferred Roku to Fire so bought myself a Roku Ultra to replace my Fire Stick. The Ultra specs are closer to a Fire TV cube but the Roku attached to the back of my TV without increasing the thickness of the TV so the TV still sits flush against the wall (my extendable and articulated mount is inset into the wall between two studs).
I like that this Roku has an ethernet port so I ditched WiFi. You can add an ethernet dongle to a Fire Stick but its a USB 2 dongle and more wires.
The biggest advantage to the Roku platform is a much cleaner home screen. The Fire Stick home screen is never ending and unavoidable advertisements. My Roku home screen just has "buttons" for the services I subscribed to.
For reasons I haven't figured out, the Roku drives my rear speakers and subwoofer better than the Fire Stick did.
In some ways the Fire Stick remote was better. It looks better and is thinner/lighter and the volume controls are on the face instead of the side. The side volume controls on the Roku remotes are too easy to bump. But this particular Roku remote uses AA batteries instead of the AAA the Fire Stick and other Roku remotes use, so battery life should be better.
Update: Thanks to WC news for the article about a Roku sale at Amazon. Started a return on my ~$100 purchase and re-ordered for ~$70. Then called CS and they were able to cancel both and issue a ~$30 credit for the original order.