Agreed with your sentiments on them.
I think I've tried all of the major players, from the original google chromecast, first gen fire-sticks up to a couple of years ago, and many roku's over the years.
I've found the roku's to be more stable with what I use them for, a couple of streaming services, including my own plex server. With the current gen working with airplay, etc, they are pretty great.
Also, I've found that the low end ones are slower, but if you go up to the premiere / premium roku's, the performance is much better.
I can hit the netflix button on the remote and it's at my login screen (user selection) within 2 seconds. The older stick I carry with me in my backpack for hotels takes a few seconds to do the same thing (once you have it on the network of course).
As others have said, you get what you pay for, pay a bit more and get faster startup times.
Also, as someone else mentioned, can you buy a non-smart tv today? especially if you want a bigger screen, better screen, etc? I bought what I'd call a mid-end Sony tv last year, has all of the built in crap, but I like my roku's, so I didn't even configure the on-board stuff, just plugged in the hdmi.and I'm good. Roku remotes can now control the volume/power once programmed.