This question might seem weird at first, but I do mean it.
I want to buy a good IPS screen for my laptop.
This is not about price or compatibility, but about quality.
I want to buy just screen, not the whole laptop.
Long story short
In (most) modern laptops, screen is connected to motherboard using Embedded DisplayPort connector. As I understand (and according to my experience), there are no vendor-specific variations, just a few standard variants (namely 20, 30 and 40-pin connectors). It is just a plain DisplayPort interface with cheaper/smaller connector and added pins for backlight and power.
What it means is that as of today, laptop screen compatibility question boils down do "Does it (physically) fit (including connector)?", which is easily answered for example by looking at photo.
So basically, choosing laptop screen should be almost the same as choosing external monitor.
Except one thing.
I have seen nothing like "AUO b156han01.2 IPS panel review". Have you?
Solution I want
I basically want a general suggestion on how to find LCD panel of specific size, with specific (e.g. 30-pin eDP) connector, that has desired qualities (e.g. brightness of at least 300 cd/m²) and does not have problems like obviously uneven backlight or wrong colors.
The obvious solution "search for laptop and then buy original panel" will not do, same way as searching for preassembled PC with everything included will not do if you only need a monitor.
A few days later, I suspect that my question is pointless.
There is no such market as "generic screens for laptops".
You often can by a laptop without HDD or RAM, but without display? I guess no.
So, chosing a laptop and only buying screen might be the only solution for now.
Let's hope I am wrong.
Now question is closed. I kind of suspected that less general questions are expected :)
Nevertheless, I might have found something:
Lenovo Y50 has such a bad screen that very long forum threads appeared that are dedicated to replacing it, and these threads have quite a few useful links.
I currently do not have time to explore these links, but I got a general idea:
If you search for display panels in general (including LED matrices, text LCDs with serial interface, industrial displays, etc.), you will find some sites that offer laptop panels too and they will have quite some information on these panels.