How long to cook pork chops sous vide?
A minimum of 4 hours isn't necessary. Pork chops don't have that much fat on them, don't have much tough tissue, and since their tenderness is on the same sort of level as decent steaks, I would cook them for a short time sous vide, not a long time.

As you hopefully already know about sous vide:


The duration of cooking isn't just "until it's safe to eat," but also about "how long it takes to convert collagen to gelatine" aka. "how to make tough cuts soft." A tough cut could already be "safe to eat" but still require many hours before it is "tasty."
Also, the duration of cooking will change depending on the
thickness of the cut. Keep that in mind: a 2cm thick pork chop will
cook faster than a 4cm thick pork chop. Also, a cylindrical item will
cook faster than a cuboid of the same width and height. Science!
The higher the temperature, the less time you need to cook it.
The tougher a cut of meat is, the longer the cooking duration is, to turn
that piece of meat into something tender.


If you don't already know those things, well, you do now! Also, go do lots of reading! Douglas Baldwin's Sous vide guide is a fantastic beginner's resource, also highlighting the (bacterial and parasitic) dangers and how to avoid them.

So what happens to a lean, decently tender piece of meat that you cook for a long time? Well, I've made mush before. You can strangely make cuts of meat both drier and mushier. Granted, it took 36 hours, but it can be done ...

I would cook the chop for 1 hour at 130 degrees F (54.4 degrees Celsius) for something that's quite pink, because I would be sacrificing some pink when I sear it on a pan afterwards.

I would cook it for 45 minutes at 144 degrees F (62.2 degrees Celsius) for something that has just a small amount of pink, because I wouldn't be searing after (for instance, I would be crumbing and deep frying after.)

I would cook it for 4-8 hours at 134 degrees F (56.6 degrees Celsius) for something that doesn't matter what the colour is, I am probably mixing it cubed in a curry or something, or I just really wanted to see what the texture was like. 

I would also refer to Douglas Baldwin's guide on pork and table of meat thickness and cooking times, because that's a good idea. You can see he mentions both a quick and a slow method (13 min+ depending on thickness and temperature, or 12 hours slow.)

TL;DR: All the times and temperatures you mentioned will be adequate to safely cook the meat, it just depends on the final texture and style you want.