personally none of these options are any use to me due to different issues
fraps works the best ingame sometimes but also initiates elevation prompt so it's a pain and it's buggy with win seven losing it's screenshot button allocation.
and none of the the other options are any use as I always play fullscreen and need to screenshot with a single button push and no prompt to save.
If the snip utility would screengrab with a button push and autosave to a specified directory with no prompts then it would be perfect