www has involved into such a monster that sometimes, nobody knows what is where, where it comes from, etc...!
nicko, disney, cnn, discovery, bbc, etc. - each one has a hundred or a thousand versions, peculiar to each country or langauge or resolution or paid/free.
what "xyz" iptv like cloudtv do is to somehow tap into whatever is available and workable, then package them for sale via vpn. stability or legit over time, who can guarantee? then again, given how fast tech change and the price u pay, they may be worth it for the individual - for as long as it works well.

you surely need to find the right box that can do the right things that u want. if mandarin is not wanted, a lot is eliminated. if canto stuff is wanted, i suppose there r only these options or a combination:

.. astro wahlaitoi - pay or foc with aotg
.. hypptv scm, red - ruby pack foc with unifi10
.. azdrama browser - foc
.. azdrama via xbmc - foc
.. csplayer - asian domains incl azdrama, koreandrama, japanesedrama, chinesedrama, drama.se, other vod, p2ptv - foc (?)
.. paid iptv packages - how good, how big library, how good for live and vod...

the canto-eng subs combo is in demand in malaysia and malaysia only, i think. elsewhere, mandarin/jap/kor-eng subs are far more popular.

Differences between Android boxes is a lot despite running the same base OS. Choosing based on what you want means buying a box based on your preference.

*Like to root, tinker? >> Buy box with great online forums support.
*Games? >>> Buy box with quad-core, minimum 2GB RAM & 16GB internal storage, powerful GPU to handle intensive games.
*Media? >>>> Buy box that supports various audio & video formats you interested in playing. e.g. AVI/MKV/WMV/MOV/MP4/MP3/WMA/AAC... etc, even ISO & 3D files.
*Future OS upgrades?>>> Buy box from recognized manufacturers who offer such Google, Minix, Amazon, Himedia, etc.

See where I'm going with this. Its like buying a car, all cars main purpose is to move from point A to point B (*Run apps*), but some cars do that better or worse than others. You don't buy a Viva when u need an MPV and vice versa.

Yes you can install XBMC/KODI on your phone/tablet and hook that up to your TV. But then means your phone is no longer close to you and you can imagine what happens when you get calls or have to reply sms. Pause media, unhook phone, do function, plug back, wanna go sit down, then msg come in again... . I've got KODI running on my tablet for out of home/bedroom usage, with a box connected permanently to the TV in the living room. Just convenience really, nothing more.

good questions! u r definitely thinking about the most valid issues.

i m <1 yr using androidtv boxes, but i'll comment as best as i can...

... no, not all boxes are built the same alto they may have same specs. manufacturer's firmware makes quite a difference as typically, it bundles with their inhouse apps which can't be used on others. e.g. some have certain chinese tv app which can't be copied onto a diff box. another example will be say xbmc - some boxes are custom built around it, other boxes may require additional settings. may not run as smooth. usually, you can't have it all but given some learning, trials and hours of testing and tweaking, you can get a lot.

... android mini-pc... u mean those sticks? typically, small handy units are limited in many ways, e.g. can't pass through hd audio or resolution max 720p. unlike full boxes, they may not have features like ethernet, digital audio, multiple usb ports, gaming, remote controls/keyboards. take note androidtv boxes typically come with usb playback media player, hd video and audio capable. some can now handle 3d and 4k.

yr handphone, yes, u can install xbmc, it will work becos these android apps were built for handphones. i have not tried on phone->TV but hv tried ipad->mirrorTV. i will say there is a difference - the box will deliver better video and audio probably due to better hardware, firmware and upscaling.

if the question is "why buy a box if a small stick or hnadphone can do it", i 'll say...
.. if light user, not big movie/tv fan, can do
.. if mid-heavy user, the box serve a great purpose

hope this is useful. others, pls comment!

english stuff, plenty. xbmc alone give you more than u can watch. and xbmc works on most boxes.

mandarin stuff - plenty, many apps work quite well for live tv, vod movies and tv series. some require membership/paid to get all of it, some u get all but may not last long due to changing regulations.

canto stuff... this is harder... there are some canto stuff tied with the mandarin apps but most are dubbed. eng subs, rare. but, you probably can find a lot more canto vod in paid iptv. these, i cant help as i dun use them.

canto stuff or yr parents, i doubt it will work well with free apps - not much available; some are way too old; some work only with browser -cumbersome navigation. having said that, i am not much into canto stuff, best others who have those goodies share with you the details.

as for brands/models, there are dozens... i hv no idea about most of them but will suggest u check out these threads, may be useful for you. all the best.
https://forum.lowyat.net/topic/3201002/+260
https://forum.lowyat.net/topic/3276304/+80

cs player should work, but only for 7-8 days trial, after which some donation needed to revive it - i din go for it, so now no more.
try popcorn time - while being "shut down" now, the android version still works. pc version is dead.