Screen

Both Screens are bright and crisp. They both have high resolutions and are easy to view.
The Galaxys S2 has samsung top mobile screen; the Super Amoled Plus with a 480x800 resolution.
The iPhone 4S has apple's Retina Display that has a 640x960 resolution.
The main difference in the screens are their size. The iPhones screen is to small for modern day smartphones. 3.5 inches just isn't enough for playing games, watching movies or even everyday use.
The S2 has a 4.3 inch screen and is what i think is perfect.
Even though the iPhone has a higher resolution it is too small to take advantage of and i have to say the Galaxy s2's screen is the winner.

Winner: Samsung Galaxy S2