How do the screens look when there is a big bright window BEHIND the monitor?
Thats what i have right now, and my current monitor works okkkk but gets a bit dimmer when the sun is coming straight at me.
Part of what you're experiencing is probably your eyes adapting to the incoming light. When your iris closes down because of the sun, the screen looks darker. Part is also due to the display, which I'll try to explain below. I'm about to say the same thing in a lot of different ways here, hoping one way makes sense so if it sounds redundant, it is...
The difference between the matte and gloss is the type of reflections they generate. Matte gives a diffuse reflection, gloss gives specular. On the gloss, incoming light will bounce off like a ray, and on the matte it will scatter in all directions.
With a glossy display, you should be able to look at a reflected light source and actually see what it is, like in a mirror. The reflected light will overwhelm the light being generated by the display itself. If you move your head, the reflection will move because the reflection is directed along a specific angle. On a matte display, a light source will spread and be mixed with the light generated by the display. Blacks become grey, more of the display area is effected by the light source, but the display image will hold its own better.
Basically that means that a focused light source (bulb or sun) directed at the screen from behind you will strongly effect a localized area of your screen (but only that area) on the gloss, and effect your whole screen on the matte but but more evenly across. If you fired a pellet from the light source and it would bounce off the screen and hit you in the eye, then the light from that source will be highly reflected off the gloss. If the pellet would bounce harmlessly past your head, then the light won't effect your view. The matte display is more like the effect of a water jet from the light-- it hits the screen and sprays everywhere, including into your eyes.
For ambient light, coming in from many directions (such as your case because the sun lights the room), the matte display will tend to wash out because some of the light from all directions will come off the screen back at you. The gloss display will maintain contrast unless there is a strong reflector behind you, such as a bright white wall, in which case you could focus your eyes on the wall in the reflection on the glass. If the reflector is far enough back, it won't effect you much because your eyes would have to change their focal distance significantly to see it.
Think of the gloss display as looking at a window. If you have more light behind you then you'll see the reflection, if there is more light behind the window you'll see it come through. For a candle in a dark room, you'll mostly see the outside, but you'll also get a strong reflection of the candle.
