What's your favorite video game sound effect? From the ping sound of Mario crabbing a coin. To the ring of character's portrait when he levels up. Anything you can think of. Here's a ... thing... I don't know what you'd call it, but it might help.
Whenever you had swung your sword and hit something with it in Legend of Zelda: Skyward Sword, it made certain type of a screeching noise. I loved it. It truly made you feel that you were using a sword, and not some other kind of weapon. xD I also liked the sound effect that your whip made. It sounded exactly like the way that a whip would sound in real life—wapish! The mega buster SFX from Megaman Battle Network series was one of my favorites, too.
My favorite SFX has to be from PSX Doom, the shotgun was always that SFX that I will remember. compared to the PC version, it sounded a lot more realistic, especially when you were in an area that had a lot of echo.
Another great SFX is from the game James Pond 2, whether you are grabbing energy or a life. it just felt like relief sometimes.