I hear lots of great sounds, but at the same time, there are sounds that are so close to being amazing sounds. For example, Tyrndamere's spinning blade sound effect is candy for my ears. The same goes for Cho' gath when he devours something (sounds like he enjoys it). Those are unique sounds, memorable sounds, and they stick out in my mind. Other sounds, not so much.
When I listen to other sound effects like Rammus's Powerball, it has a spinning sound, but it lacks a sort of evisceral quality to it. I don't feel like it is going to cut something up like Tyrnd's spinning slash. Take Sonic the Hedgehog for instance. When you rev Sonic up, you can hear him getting faster with each push of the button. Don't get me wrong, the Powerball's sound is in the right direction. It has a sawblade quality, but I feel that with a an extra "oomph" it would get me the same satisfaction as the spinning blade. Keep in mind that I am only using the Powerball as an example and that what I am stating is simply a general overall feeling of the different sound effects in the game.
Perhaps a poll or voting system to see what new or old sounds receive the best responses?