You get what you pay for i think in this sort of thing but the use is what you have to also consider. Early firesticks as already pointed out won't do 4k. There again if you are streaming 4k the file sizes can be enormous so three considerations. Firstly can your internet handle the speed needed. dont forget a 10mbps is only around 1meg a second or sixty megs a minute. Now if you are watching a film of say 20 gig it needs a fairly fast internet to steam Second and more inportant is are you wanting to watch netflix, Only a couple of boxes plus the firestick are supported and trying to watch nexflix in full HD is hard enough let alone in 4k. But on most boxes it is almost impossible to watch in 4k. Do we only want to use it for other services and not interested in netflix. Then you options are much wider but still the quality is dependent on what you pay. minix, and the shield, Are most likely the top boxes and you wont get any lag from these. But only the shield is supported by netflix. I realise that you can work around the apk for netflix but i dont think you can get it to play in full 4k on unsupported boxes. Other considerations might also be VPN. This can effect things in a very cheap box and will definitly effect things if it is installed on the router. I might be completely wrong on this but its just my thoughts