The Sharp obviously come packing with more advanced features , with a more hefty price tag .

The Toshiba TV has left the race a while ago , but in this case it is the cheapest Android TV model you can find now  ( RM 2400~ ), without the support for HDR . Although at this price range HDR will not make a difference than SDR ( Standard Dynamic Range )
Is there any particular reason you are obsessed with Android TV ? The Android OS are sluggish , unresponsive and more prone to frequent crashes .
Just look at all the high end Sony TV  , despite having some fantastic performance the Android OS has been dragging the TV down from their review scores.
Almost every single Sony TV review mention some horrible experience about their Android OS .
Since you don't use HDR content at all , the WCG and Higher brightness shouldn't be a concern , as all 3  TVs have more than enough brightness for SDR content.
Save yourself some money , grab a mu6100 and you have a good deal.

Kodi and netflix are typical apps , as such they can be installed on any smart TV , specifically the 2 units you mention.

Edited : Kodi is not available on NON-Android OS , therefore you cannot install these App from the the TV 's appstore .
It is hard to tell a difference from a TV display in the shop , because TV merchant are known to play with the TV settings in order to bait buyers into buying the TV.
We also don't know what settings they use in the shop unit . Perhaps the Samsung TV you saw has set up for higher sharpness in the menu ? 
When we said better, the difference is so small most people will not notice it . Not to mention Sony's slight advantage is virtually non existent here because Samsung has excellent upscaling as well.
For a budget of 2-3k , x7000e and mu6100 are generally the most solid choice in Malaysia . They are still superior to the other China brands in terms of TV design ,build and features .

If you want a VA panel , go for mu6100 . For IPS panel ,go for x7000e .
55 inches of x7000e is a VA panel . 43 inches version of mu6300 is an IPS panel. 
P/S : x7000e is slightly better for sports viewing and mu6100 is slightly better for gaming

right..

most smart tv's come with and can do youtube, netlfix, browser.

new LG is said to be able to do astrogo.

sony and sharp androidtv tv's can do the most - besides youtube, netlfix, kodi, can sideload astrogo, unifi playtv... just about every android app.

you are probably right to say that the cheap androidtv tv's may be problematic - it's all about good and lousy firmware.

i have use my sharp for 3 years now, all is good.

of course, will need some work and patience to get all the apps working.

much easier for someone who has used android phone, tablet or box.

There are apps that will be rejected by the security of the androidtv system.
Such apps are usually highly suspect, maybe infected, meaning the security works.
The common popular ones are fine.

There are constant minor upgrades done ota or over the air, u dun even notice it.
Major ones, say android5 to android6 or android6 to android7, u will be prompted, need to activate manually.
And that is rare, only once in 3 years, unlikely to happen again.

A last word for u... if u do not know android apps much or hv little interest, androidtv will be of little use to u.
If u r big user, it is as good as any rm500 android box u buy separately.
Minor users use it to watch youtube 4k or bloomberg news.
Major users can watch hd videos with kodi, watch world cup matches live in 1080p - foc, using androidtv.