Thanks for the advice.... I know what i doing... I am a IT guy too... Now trying to know more in android and i trying to use it to do more things... Want learn flash, root, unroot and macro...
I see. I am not an IT guy myself and not a hard core hacker. My initial goal is to run Linux on some boxes and also play with generic USB device under Android with rooted box using Termux. Termux is a small Debian distribution under Android and it needs root access to run libusb. So my first 4 boxes are all generic rooted box.
And then I bought Tanix TX5 Max and TX6 to have access to different CPUs with my existing boxes. Also want to see if better brands offer better quality.
In that case yes you want to use more popular generic boxes and not really proper but more restrictive boxes like Mi Box S and Nvidia Shield TV.
There are a lot of such boxes where people have developed custom FW.
1) S905W low end boxes like Tanix TX3 Mini and X96 Mini, cheap yet there are many custom FW including Android TV OS. They are also popular because of the possibility to run Linux distributions like Armbian Linux or LibreElec. Cheaper and more Powerful if you are more into Multimedia application.
2) S912 boxes, more powerful. Good support under Linux as well. Android TV os is available for popular boxes like Minix NEO U9-H.
3) RK3328 boxes, limited support under Linux. Android TV OS is also available for some boxes.
4) New S905X2 boxes, no support of Linux yet. Android TV OS is available. Beelink GT1 Mini, H96 Max X2 and X96 Max seem to be popular for this purposes.