OP, only you can answer this question. What do
you want?
This is a pretty biased crowd. You can't get objective input from much of this crowd. Apple has not yet endorsed 4K, so the crowd bias is going to be against it. You might as well post "should I get a Windows or Mac computer" or "iPhone or Android phone", etc. The majority is always going to argue with whatever Apple has, appears to endorse or appears to be embracing soon. NFC was "stupid, gimmick, etc" before Apple implemented it and then we wanted to boycott stores that wouldn't let us pay that way. Bigger screen phones were abominations, stupid, fragmentation, "99% don't want", "man purses" & "pants with bigger pockets" until Apple rolled out bigger-screen iPhones (BTW, I still don't see much in the way of man pursues and pants with bigger pockets- did nobody in America buy those "abominations"???).
At one point Apple rolled out 2 new iPad models: one with retina and one without. The crowd passionately argued why retina was must-have on one but not needed on the other. Then, a year later, the latter got a retina screen and the crowd argued why retina was must-have. It is the nature of the crowd to default to whatever Apple has, endorses or appears to be embracing very soon (I'm looking at you split screen multitasking and 2GB RAM, the former being gimmicky and stupid on tablet-sized (competitor) screens and the latter being "completely unnecessary" because "Apple optimizes iOS so well that it doesn't need more than 1GB RAM", "who wants double the RAM at the expense of battery life?" and other so commonly-spun rationale(?); etc.)
Buy a 1080p TV and if Apple endorses 4K the next day with a 4K-capable
TV 4, a new iPhone camera that can shoot 4K video, etc, a lot of these same arguments against 4K will flip... just like they did back when Apple clung to "720p is good enough" (for HD) and the majority sided against 1080p (gimmick, don't need, can't see a difference from an average sitting distance, "the chart", storage requirements, until broadband bandwidth is expanded everywhere, until
everything in the store is available at 1080p, etc). Then Apple endorsed 1080p with Apple products shooting and playing 1080p and the whole "720p is good enough" argument evaporated. 720p was so right before Apple embraced 1080p and then 1080p became the new "so right" (again see bigger-screen iPhones, no iSight camera in iPad 1 vs. FaceTime in iPad 2, 24-hour battery life in Samsung smart watches being ridiculous but 24-hour Apple watch is perfectly doable, and on and on). Now 1080p is playing the role of 720p and 4K is 1080p. Apply the same arguments until Apple goes 4K, then evaporate the "1080p is good enough" sentiment. Repeat with 4K vs. 8K.
Consider what you want from this TV now and in the next few years (upwards of even 5-10 years). Note where technology is going rather than where it is or has been, as TVs tend to be a longer-term-use product than- say- individual iPhone models. Then choose the one that YOU want. If the difference between them comes down to only a few hundred dollars, even $500 difference for otherwise same-size screens would be like spending an additional $50/yr over 10 years or $100/yr over 5 years (of use). Save up the extra dollars if you want the added resolution or use store same-as-cash financing to get it now and spread the extra out in a slightly higher payment during the same-as-cash term.
All that said, take that "stupid", "gimmicky", "abomination-sized" iPhone 6 down to your favorite TV retailer and buy the one you want with that "nobody needs", "stupid", "gimmicky" Apple Pay. If you want to please
this crowd, by using the "best iPhone ever" and the "best payment option" ever, you'll have already run with two of our recent, collective flip flops and- depending on your choice of TV- may simply beat us to our third.