That is a very interesting and opposing notion. From this thread the thing that stood out a lot was refresh rate and that's mostly what I planned to look into first from this all. Thank you.

Of those two the 4K, definitely. The issue with reliability usually rest with people, they max that things out, high brightness, max volume, etc. Yea, brand/build quality makes a difference, but imo most thing are good enough now.

Neither. Both brands are absolute garbage. You dont have to go out and buy an expensive and overpriced bravia but a samsung or LG or hell even a lowly Vizio will have alot better picture quality, better features, and better craftmanship than either of those two turds. Trust me, as the saying goes "you buy cheap you buy twice".

True 100/120Hz or 200/240Hz displays have a shorter reaction time. You wont benefit directly from that in terms of input lag, but it can be helpful in some ways in ters of picture quality.

Black Frame Insertion, basically blinking or scanning backlights help to reduce stutter/motion errors of hold type displays.

Problem is that companies started to calculate in a ridiculous way, combining BFI, frame interpolation and refresh rate to get higher and higher numbers.

Does it need to be a fast panel? Gaming only not neccessary, but with 24p Blu Ray or VOD you wont have that much pulldown issues. Reaction time of the display might acctually benefit picture quality.

Frame interpolation (which is calculating  frames between frames) is what smoothes motions, leading to the 'soap effect' if it's to much/to harsh. It definetely isn't a thing for game mode though because your tv will need to 'know' some frames to calculate the new frames>laaaag.

So there's BFI left. That's basically a standard today.

Now for panels and brands: Not every brand actually manufactures panels today. Sony buys panels. Toshiba buys panels. Panasonic buys panels. And yes, they also buy taiwanese and chinese panels. Hell, some of those brands have been improving a lot over the last years. So what's the issue?

1. Super cheap tv's often have more pixel errors. Really sucks with always on (sub-) pixels. One small red dot can piss you of. Two or three? dead pixels aren't that bad though. You often wont see them at all.

2. Calibration, especially color calibration. You want a greenish yellow? Purple and pink instead of red? That's what you get with to much blue for example. Even brand tv's aren't perfectly precalibrated. But they usually give you way better options for calibration.

3. Backlight quality. Even some not so cheap brand tv's have backlight issues. The really cheap ones often have way more. There are some good, cheap brand tv's with few to no issues. My parents bought an entry level Toshiba some years ago with no clouding or dirty screen effect.

4. Reliability. It's always an issue. But really cheap might also mean things like the LED's for the backlight are cheaper with a shorter lifespan.

4K

That makes sense. Those are interesting sidenotes for "what matters 'n' why". Clears things quite a lot. If I see dead pixels, poor calibration, or poor backlight I will return it. Might just need a protection plan. I have to ask, where did you learn all of this? and which tv is better or do you recommend another? I don't use 4K and don't plan to. So my gut tells me "get the 58".

Sounds stupid but i'd recommend a tv you like. Not without reason though. At the very least if you're not only using game mode every manufacturer has kind of a specific picture look. That's not neccessarily bad with 'no name' tv's.
4K or not 4K, you might rethink that some day, so:

That 4K one looks pretty much like one that's sold with another name in Europe. If it is the same picture quality overall isn't the best, looked like scaling deficits. One benefit might actually be it has 4 HDMI ins and at least some of them should have HDMI 2.0.
Here's the but. But there's still many 4K TV's without full UltraHD support. So no high dynamic range for example. And how much resolution you need or benefit from actually depends on screen size/viewing distance ratio.
If viewing distance/screen size is 2 or bigger people should totally forget 'sharper than 1080p'.
One small thing i noticed, the 4K one has 250cd/m2 max. brightness. That's a bit low for lighter environments.

Now the 58": It's a bit cheaper and a bit bigger. It's not that much bigger though. Actually 11% more screen space isn't such a big deal. One real downside, it's got only two HDMI ins. If you're already using an AV receiver that doesn't matter. If not, how many HDMI's do you need? You might ad some HDMI splitters.

If two HDMI is fine for you the slightly bigger one is worth a try. If it's not sufficient for you, spend a bit more money for something like an LG or Hisense (yes, chinese, but they've been getting better over the past years). Seems like Wamart sells some refurbished and not so expensive ones.
http://www.walmart.com/ip/Refurbished-Hisense-55H7B-55-4K-Ultra-HD-2160p-120Hz-LED-Smart-HDTV-4K-x-2K/50213185

About your question:

I echo others when they say to avoid BOTH televisions.

BTW, what's your budget?

http://www.rtings.com/tv/tests/video-games?uxtv=18f0