lets see here...

1.Half Life

2.Halo(it was hard to choose between halo and halflife)

3.Call of Duty

4.Final Fantasy

5.Dawn of War

6.Metroid

7.Legend of Zelda

8.Mario

9.Kirby

10.Sonic

never played COD 4 so my vote is completly based on my experience with the Orange Box.

The orange box is really good but after you beat the games they are kind of boring. That is unless you learn to use the developers console. This provide endless more opportunities for fun, especialy in portal with its bonus maps.