Don't know if you guys are serious, but latest wireless mouse have a response time of about 1ms, which is faster than the 2ms response time most wired mouses have. You can say whatever you want, I've played FPS and RTS always with a wired mouse, and then I switched to Razer's Mamba and I never felt any delay AT ALL.
Only con is that the mice is heavier than a wired one because of the battery, which sucks for playing osu!, so yeah wired wins, but don't go yelling LOL WIRELESS MOUSE = DELAY because you're living in the past guys, wireless mouse have achieved zero lag already, unless every mouse producer is lying.