after 8 weeks using this sharp lc50ue630x uhd 4k tv, let me summarize my experience with it:

.. good video quality; 1080p, bdmv, bluray, 4k videos - excellent.
.. good upscaling for 720p, 1080i videos
.. vibrant colors.
.. the android within is good - capable of doing any 2/16gb lollipop 5.1 can do.
.. the android within can take a good no. of apps, performance is no lower than any android box.
.. works very well with netflix hd/uhd4k even on wifi.
.. works well with iflix (iflix is all sd but when upscaled, very acceptable).
.. hypptv 1080i channels like bbc earth, travel & living, natgeopeople come out sharp and bright.
.. usb playback can handle all common formats incl mkv, m2ts.
.. toslink digital output is dts/dd capable.
.. a surprisingly cool tv, does not even get warm.
not so good:

.. somehow, i find the dark scenes a little too dark, the bright scenes a bit too bright. don't know if this is a characteristic of all 4k tv's..?
.. all hmdi's video setting is restricted to a choice of std, movie, pc, dynamic or dynamic fixed. u can change the variables in each set but that will apply to all hdmi's. this is not as good as previous models where u can change the variables in each setting for every hdmi input and save as user1, user2, etc.
.. all inputs and outputs incl hdmi, usb, optical, lan are at the back of tv, not side - access difficult for wall mounted cases.
overall, i am very happy with the tv.

Currently, SHARP is being bought over by Foxconn. $6 billion deal. At the moment, the deal's shaky as Foxconn isn't liking some new found information.. So support future-wise, yet unknown. Don't let that put you off buying a SHARP TV if you like it.. We are not talking shares here.. 

i am not concerned with the foxconn-sharp acquisition. such biz deals happen all the time and does not change issues like warranty that quickly. moreover, sharp warranty is only 2 yrs, the extended yrs are usually by insurance co. i have bought 5 sharp tv's in my life, never had any issue with them for years.

since u r thinking of some android box, this sharp ue630x comes with a pretty good built in android. u can start getting to know such a feature with the tv. the difficulty is u r starting from scratch with little help whereas if u buy a box, the seller can help u. but androids are androids - they all work the same way whether in a tv, box, tablet or mobile phone - should not be hard to find someone to help u.

ue630x base price, i think now should be... 50" <rm4k, 58" <6k, 65" <8k.