Quote Originally Posted by Don Julio Anejo View Post
Blue works best on mana-gated lane bullies. Olaf, Ryze, top; Ziggs, Lux, mid, etc. Kinda superfluous on assassins. On Cait 8 out of 10 times I'd actually rather have blue than red at any point except late-game teamfights since she becomes so much stronger when she can spam traps and EQ combo for free poke.
Cait is stronger with Red than Blue at most stages of the game, though. At level 1-3 especially, Cait with Red is almost a certain zoned enemy ADC unless the support has sustain or the enemy duo significantly outplays you, while Cait with Blue isn't as problematic to deal with(and she was outpushing her opponents anyway, so added waveclear isn't a huge benefit).