Can Byakuya overcome Aizen's Kyoka Suigetsu as easy as he overcomed Koga since both of them are based on illusion?
If Byakuya's Senkei will always find illusion based shinigami, does that mean he can overcome Aizen's Kyoka Suigetsu illusion just as easily with his Bankai?


Not even close. Here's why:


Both illusions are water based however while Byakuya's Senkei uses his reiatsu, Aizen's Kyoka Suigetsu is just it's power.
We also have to note that Kyoka Suigetsu manipulates 5 senses which is something Senkei  can't do.
You can't see Aizen activating his Kyoka Suigetsu in a verbal way. That is because you as the viewer and characters in the show can't see. The moment he activates it you are done. You are in Aizen's world now. Sad thing is you don't even know it.