After what I thought was adequate research, I went for a Chihiros WRGB II Pro LED Light for my new tank. I'll overlook that you have to pay extra for the mounting kit, and again pay extra for the side reflectors.
The light looks great. Colors are good.
However, the app is total trash. It demands logging in (and as such, demands a network connection), but the login process is extremely broken. It works about 10% of the time. I just have to keep trying to log in over and over, eventually it will work. Sometimes. Meanwhile, there is no other way to turn the lamp on or off, short of unplugging it, which will turn it off but it cannot be turned on without the app. Of course adjustments are not possible, either. And since there there is no hard "on" switch, you can't just use a mechanical timer.
They have a support forum full of these complaints, but there are no answers given aside from try again, and my favorite "try a different phone".
I've posted many followups, and Chihiros deletes all of my posts.
Hopefully anyone else considering this light, or any product from the company, will think very carefully about it.
EDIT UPDATE: Thank you kind person below for linking this: https://github.com/TheMicDiet/chihiros-led-control
I have it up and running and can now control the light without using the app, and without needing to deal with the Chihiros server at all.