Which is better value for money?

[KingJosh]

iMac 21" or iMac 27"?

 

[waloshin]

For me the 27 its huge with a better resolution.

 

[KingJosh]

Thanks for that, is there much of a difference between value? I am asking on my brother's behalf (student). He wants one for guild wars 2 and school work. He would like the 27 of course and can afford it but he has other things to use money on as well so he is wondering if it is really worth it just for the bigger screen.

 

[Vantage Point]

The 27" has a pixel density of 110 ppi (pixels/inch), the 21" has 102 ppi. Not that much difference in resolution but big difference in size. The 13" MBP has more resolution at 113 ppi and the 13" MA has more resolution at 128 ppi. A 27", being physically larger, will be pushed back further from the user than a 13" and that further distance can make the apparent pixel density smaller but the FOV (Field of View) of a larger monitor changes the experience.
http://en.wikipedia.org/wiki/List_of_displays_by_pixel_density

Knowing these differences can be important to get what you want.