OLED is great for latency, in such an extreme case as a VR HMD. Oculus chose well! Pentile IS a problem for VR (FAR more so than for a phone because the pixels are magnified)--but it's still the best compromise possible for them to use today.
On phones, people get used to the Pentile problem. Or measure other things and ignore it when evaluating. Glad I don't have to!
Remember, all screen technologies have pluses and minuses. Some posters here like to pretend Apple's screen's weaknesses ("only" 401 DPI!!) are a problem while other brands' weaknesses don't exist. Others will pretend Apple's solution (rendering high and downscaling on the Plus) have no impact at all. Not true: that choice does have an effect. (It's likely still the right choice, if early experiences are an indication.)
Also remember that Samsung at al don't sell that many of any given high-end model. Apple, and Apple alone, has to choose a display that can be made in MASSIVE numbers no other single phone model requires.
Out of those engineering realities comes the result: not abstract spec numbers but the quality (and performance) that are delivered. And the iPhone 6/Plus deliver outstandingly.
That may have been the case with older pentile displays. I had the Note 2 and could barely see it. My brother has the Note 3 1080p and I can't see any difference between RGB and pentile arrangement. You won't be able to see any issues with a 2k display. I'm not sure if you've seen any Galaxy phones recently (probably not) but it most definitely not a problem at all.
You just seemed to have ignored my previous point and harped on saying the iPhone display is the best when it clearly isn't. Subjectively and objectively and where it matters, monetary stakes. Oculus and Samsung billion dollar companies with billion dollar backing have chosen it. DisplayMate a 3rd party site objectively analyses screens rated it as the best. But you still don't believe, I don't know what else to say tbh.