Up until recently, 4:3, because that's what all my screens had used (except the one I had connected to the Xbox 360, that was 5:4 - 1280x1024, so I obviously used that resolution). Since my acquisition of a larger screen however, I use 16:9 for games that support it (which broke my earlier vow to go with 16:10 when I finally started going wide - I blame the fact that it was a second-hand screen and the price was cheap).

You should always use a game's original aspect ratio if you are not dumb :-P

How do you propose I'd do that on a 16:9 monitor with a 4:3 game?

Pillarboxing. Aka black lines left and right of the screen.

In which case letterboxing (black lines top and bottom) should maintain the correct aspect ratio, as well as the correct FOV. That should help with the eye problems.

Yes, Mich, they do that, but I just can't get used to them for long. :)

I hate those older games which offer fake widescreen, ie. selecting a widescreen mode or resolution does indeed fill the 16:9 screen, but in practice it simply stretches the original 4:3 graphics to 16:9, making circles to ovals, characters fat etc.

PC games like:

Halo
GTA 3
Wheel of Time (and probably other Unreal engine games)

In these cases I rather use the 4:3 resolutions with black bars on the sides, as I feel that is what the game was meant to be run at.

And then there's Serious Sam... What the heck is the widescreen option in it supposed to do? If you enable it, you still have only the basic 4:3 and 5:4 resolutions, and all you get is even a smaller "widescreen" window to play the game on, where on top of the bars on sides, there are black bars also on top and bottom. Huh?

I guess that's the main advantage of the Serious Sam HD remake to me, it supports widescreen resolutions properly (yeah yeah, overall it looks better in other ways too, but I would be happy with the original SS graphics, if only it had working widescreen mode).

Yeah the image fills the screen for me. And they don't look fat unless a character was made to be fat. I looked at the screenshots and they are not so bad. I find the people in them a bit too tall. Their legs are a bit too long. The woman in one of the screenshot has a barbie doll body(really long legs) and that is just not realistic. I will post screenshots here soon so you guys can see what I see.

I´m using 16:9 (1920x1080) whenever it´s possible without any problems ,like Vert-, streched image and others.
If it doesn´t work I go for 4:3 aka 1280x960.

Whatever is native on the screen.

If the 1024x768 image fills your widescreen laptop screen, then you are not playing games as they are intended by the developers / artists. If you see a circle in the game, it will look like an oval. It is the same as viewing an old 4:3 TV show stretched to widescreen on an HDTV.

I'm gaming on a Dell U3011 30" DFP @ 2560x1600 (16:10), so my preference whenever possible is to run games in the native resolution and aspect ratio of my display. Surprisingly, a lot of games do actually support 2560x1600 including some games from the 90s, which is nice because they almost certainly had no way to test the games at this resolution way back then.

For games that do not support this high of a resolution I try to configure them to 1920x1200 (16:10) if they support it, then I fall back to 1600x1200 and lower resolutions. I always try to configure a game to the highest resolution and colour depth that it will support, and in native 16:10 or 16:9 if possible, only falling back to 4:3 if there is no other option. If a game wont run well at full resolution with all effects cranked to the max, I will either drop the resolution down a notch or two or I'll disable some of the 3D effects to try to strike a balance that I perceive to work best for a given game. For FPS games I'll favour resolution over effects, but for RTS or other games were high level of detail isn't super critical, a drop in resolution might be better.

In order to use the best possible resolution, or widescreen modes however it can be necessary with some games to search the web a bit. Some games have hidden config file settings or similar that are not visible in the game's built in Graphics Options configuration screen, but which can sometimes be configured through manual editing of the config file to get the best gaming experience.

For legacy games that only support 4:3 aspect ratio, by default I let my monitor stretch the image to full screen in both directions to get the largest possible picture, and if the game looks distorted or if gameplay is less than stellar due to things being stretched, I'll tweak any game options if possible to sort it out, and worst case I use my monitor's OSD to modify the stretching method or disable it and retain 4:3.

That won't actually work. If you you are viewing a distorted image the only way to capture what you are seeing would be to take a picture of it. Actual screen shots will "self correct" if the view's screen is displaying aspects correctly, because the problem isn't happening on the pixel level. Some games may be able to add pixels to do the actual distorting and that would show up in screen shots, but it's more common for it to be a monitor shape vs res shape conflict.

The big three questions are
What is my monitor's aspect ratio?
Is my screen resolution the same aspect ratio as my monitor? (if it has a native use that)
Is my monitor's display for shape calibrated correctly?

If all of those things are in agreement then distortion shouldn't be a problem, if not then it will be. I would be curious to know the specific answers in your case starting with, what is your monitor? Followed by what resolutions look right, and what doesn't? If it is a 4:3 monitor it would stand to reason 4:3 resolutions would look more correct. If looking at image on the web is distorted then even your desktop resolution may be wrong.

Nevermind.