they've a years longer track record making Roku TVs. my P607 from 2017 is still getting updates. we'll have to see if they do the same with Android TV, but they've only been selling TVs with it for a short time
An old Android TV you might be able to flash for a second life, but the extra-proprietary Roku turns into ewaste garbage.
Android has better apps and codecs support but roku has a good history of updating its software Note that recently roku has some conflicts with Google regarding youtube licensing
The Roku TV will be updated by Roku, The Android TV will be updated by TCL. There is not a long enogh track record wth TCL Android TV to know how long they will support it. So smart money would be on Roku.
Mute point. Both will have a short lived update life span and typically perform poorly. When that time comes just add a $50 dongle which will have a current version of whichever os you choose and will perform much better than the included os.