because its all down to personal preference.
visibility decreases on 1280 somehow...
i play 1920x1080 and its really hard to spot enemies vs 800x600 for example idk how to explain this...
but yeah i prefer 1920x1080 quality over all
i also noticed that 4x msaa increases my colors ... 8x msaa makes it all grayish , and 2x msaa doesnt affect anything
i play on 800x600 god res
Most people that play 1024x768 (4:3) already in game for long time. at they time, PC is not powerfull as nowadays. and monitor at that time only support for 4:3 aspect ratio . even years after 16:9 aspect ratio introduce, some people already used to play with 4:3. they're a lot new player that use 4:3 aswell, but for they case mostly they're imitating some of pro player.
I dont think that you need high fov to play cs so its better to be zoomed in
1024 stretched is smoother too me
1280x960 godlike res