[Galaxy Note II General] Kangal:
That's a dpi issue NOT a ppi issue.

DPI = basically the "zoom" level on Android. Relies on ppi, but is actually software controled through the device id (build.prop)

PPI = pixels per inch. It is NOT a gimmick, it is a form of measure.

PenTile = a way of maximizing pixel effeciency, by sharing subpixels. Great potential to increase screen resolution without the actual pixel count, thus, saves battery too.

RGB = Red-Green-Blue pattern of pubpixels. Each pixel is a block. Causes images to look sharper especially on corners of shapes (like icons).

AMOLED = Active Matrix Organic Light Emmiting Diode. Its a screen technology. Blacks are pure black, however, the colours are inaccurate and very Vivid. It relies on external light to illuminate the display, and a rear panel to boost the brightness. Great viewing angles, very little bleeding.

LCD = Liquid Crytal Display. Its a competing screen technology. Blacks are grey. Though colour accuracy can be top quality. Needs a rear illuminating panel to work. Can have issues with bleeding and viewing angles.

PPI debate = the more the merrier, its not a gimmick.

With that said there is a limit where the more you have, the lesser the effect is. And Apple would have you believe this is at 300ppi, they would be wrong. The human eye doesn't catch light on straight angles, its curved, it catches light curved. It would actually be closer to 500ppi. And even higher, even 800ppi when focusing on a large contrast object (like a tiny water drop on a black surface). For electronics, I'll simplify and say "its more complicated". The distance you hold the device plays a key role. The types of colours being shown, and if they are moving (video) then you'd need less and less ppi to have a good "quality" display. And personally I would say a person would have difficulty telling two identical displays apart showing the same image at 190 vs 210 ppi difference. As a rule of thumb, I would say anything above 200ppi is good and anything above 250ppi is wasteful.

PenTile VS RGB = PenTile saves some power and can push extra pixel resolution. RGB is straight-forward. For mobile devices PenTile is actually superior if it does offer the higher pixel count (hence higher ppi) and shaves a little off battery. AMOLED also requires one layer less, so slightly thinner devices. However, those were issues 3 years ago. Technologies improved to the point where RGB-panels can consume the intended amount of power, and that we can make the subpixels small enough to fit enough pixel count on small screens, and that each layer is thinner.

AMOLED VS LCD = AMOLED will use no power for blacks. Will use very little for red. Will use below average for blue and green. Will use above average for yellow. Will use a lot more for white.

LCD will use little for black. Will use average for red, blue, green. Will use above average for yellow and white.

Overall, it depends on what colors you're using most. On average, I think AMOLED will use less, but a session on the Internet Browser (mostly whites) will cause it to consume more than LCD.

With that said, there are a lot of technologies built on top of LCD such a various IPS, and "Super" variants. LG's 4X HD has one of the highest viewing angles, best colour reproduction, and much higher brightness than almost any display out there.

My personal Priorities:

1) Screen size = the larger the better, but device must fit into my XL hands and average pockets. That calls for minimum bezel.

2) Brightness = the more the better. I find myself outdoors/blury situations

3) RGB = my pilot eyes detect PenTile's patterns, though a high ppi (>250) it gets less obvious so I can contend with it.

4) AMOLED vs LCD = LCD. It's come a LOONG way. If its not a good quality LCD (SuperLCD2IPS etc etc), then obviously AMOLED.

So for me, the LG 4X-HD is the best screen, if they manage to create one in a 5.2 inch size, on a phone with minimal bezel (like Pantech Vega S5). However, there's even more factors when deciding on a phone/device... and part of that comes in bootloader lock status, source availability, r00t ease, custom recoveries, community support, SoC performance, radio features, quality of parts (speaker is loud?) etc etc