23 and 24 inch or even 25 inch monitors are great for 1080p resolution. 27 inch will be fine as well but it won't look as nice as the pixels will be larger and the image won't look as sharp which may affect you if you do reading, HW, or precise work on the monitor. For gaming, 27 inches definitely looks epic.
The reason why I chose the Acer monitor is because it is 24 inch (great) and also has 144hz refresh rate which will allow you to see up to 144 FPS which will help in CS:GO and other shooters (if your hardware is capable of running it at 140+ FPS of course).