HEY YOU
Tick Rate 2 should be used because...
 - Tick Rate 2 prevents unnecessary HP drain during sliders.
 - Tick Rate 2 almost always sounds correct with the correct BPM.
 - Tick Rate 2 gives you more ticks to do cool sound skinning with.
 - Tick Rate 2 lets the game know that the player's cursor is on the slider track.
Lastly, lots of cool people use Tick Rate 2 and you should use it too.