Hi! I have to be honest, I never really gave crack ships much thought, or even rank them. Off the top of my head, the ones I'm receptive to are...

1. Given that Taku and Rei know each other, I don't know if they'll count as a crackship (since usually that's between two characters who rarely interact, right? you mentioned Rai and Asato and they're sort of similar to Koujaku and Noiz, dynamic-wise)
2. MadaTaku is growing onto me (I have specific thoughts about them, but for safety reasons I shall not share them).
3. Someone brought up Kotarou and Rei before, I'm not opposed to the idea.
4. Towa and Akira would make an interesting couple.
   
5. I once considered the idea of Aoba and Shiki back when I used to do RP years ago.
6. I don't give much thought to shipping the DMMD LIs with each other, but if I were to pick one that I'd go for, it'd be Mizuki and Clear.

Well, that's all I could list so far. There's likely a few more, but they have yet to come to the forefront of my mind.